diff --git a/submodules/TelegramVoip/Sources/OngoingCallContext.swift b/submodules/TelegramVoip/Sources/OngoingCallContext.swift
index ce8c733b26..68860c76e2 100644
--- a/submodules/TelegramVoip/Sources/OngoingCallContext.swift
+++ b/submodules/TelegramVoip/Sources/OngoingCallContext.swift
@@ -728,6 +728,18 @@ public final class OngoingCallContext {
                         filteredConnections.append(contentsOf: callConnectionDescriptionsWebrtc(connection))
                     }
                     
+                    /*#if DEBUG
+                    filteredConnections.removeAll()
+                    filteredConnections.append(OngoingCallConnectionDescriptionWebrtc(
+                        connectionId: 1,
+                        hasStun: true,
+                        hasTurn: true, ip: "178.62.7.192",
+                        port: 1400,
+                        username: "user",
+                        password: "user")
+                    )
+                    #endif*/
+                    
                     let context = OngoingCallThreadLocalContextWebrtc(version: version, queue: OngoingCallThreadLocalContextQueueImpl(queue: queue), proxy: voipProxyServer, networkType: ongoingNetworkTypeForTypeWebrtc(initialNetworkType), dataSaving: ongoingDataSavingForTypeWebrtc(dataSaving), derivedState: derivedState.data, key: key, isOutgoing: isOutgoing, connections: filteredConnections, maxLayer: maxLayer, allowP2P: allowP2P, allowTCP: enableTCP, enableStunMarking: enableStunMarking, logPath: tempLogPath, statsLogPath: tempStatsLogPath, sendSignalingData: { [weak callSessionManager] data in
                         callSessionManager?.sendSignalingData(internalId: internalId, data: data)
                     }, videoCapturer: video?.impl, preferredVideoCodec: preferredVideoCodec, audioInputDeviceId: "")
diff --git a/submodules/TgVoipWebrtc/BUILD b/submodules/TgVoipWebrtc/BUILD
index 842991e710..8ea93a9ab6 100644
--- a/submodules/TgVoipWebrtc/BUILD
+++ b/submodules/TgVoipWebrtc/BUILD
@@ -1,3 +1,4 @@
+load("@build_bazel_rules_apple//apple:ios.bzl", "ios_unit_test")
 
 config_setting(
     name = "debug_build",
@@ -92,9 +93,52 @@ objc_library(
         "VideoToolbox",
         "CoreTelephony",
         "CoreMedia",
+        "GLKit",
         "AVFoundation",
     ],
     visibility = [
         "//visibility:public",
     ],
 )
+
+objc_library(
+    name = "TgCallsTestsLib",
+    copts = [
+        "-I{}/tgcalls/tgcalls".format(package_name()),
+        "-Ithird-party/webrtc/webrtc",
+        "-Ithird-party/webrtc/dependencies",
+        "-Ithird-party/webrtc/dependencies/third_party/abseil-cpp",
+        "-Ithird-party/webrtc/webrtc/sdk/objc",
+        "-Ithird-party/webrtc/webrtc/sdk/objc/base",
+        "-Ithird-party/webrtc/webrtc/sdk/objc/components/renderer/metal",
+        "-Ithird-party/webrtc/webrtc/sdk/objc/components/renderer/opengl",
+        "-Ithird-party/webrtc/webrtc/sdk/objc/components/video_codec",
+        "-Ithird-party/libyuv/third_party/libyuv/include",
+        "-Ithird-party/libyuv",
+        "-Ithird-party/webrtc/webrtc/sdk/objc/api/video_codec",
+        "-DWEBRTC_IOS",
+        "-DWEBRTC_MAC",
+        "-DWEBRTC_POSIX",
+        "-DRTC_ENABLE_VP9",
+        "-DTGVOIP_NAMESPACE=tgvoip_webrtc",
+        "-std=c++14",
+    ],
+    srcs = glob([
+        "tests/*.m",
+        "tests/*.mm",
+    ]),
+    deps = [
+        ":TgVoipWebrtc"
+    ],
+)
+
+ios_unit_test(
+    name = "TgCallsTests",
+    minimum_os_version = "9.0",
+    deps = [
+        ":TgCallsTestsLib",
+    ],
+    visibility = [
+        "//visibility:public",
+    ],
+)
diff --git a/submodules/TgVoipWebrtc/tests/TestNegotiation.mm b/submodules/TgVoipWebrtc/tests/TestNegotiation.mm
new file mode 100644
index 0000000000..a3d531431d
--- /dev/null
+++ b/submodules/TgVoipWebrtc/tests/TestNegotiation.mm
@@ -0,0 +1,705 @@
+#import <XCTest/XCTest.h>
+
+#include "api/task_queue/default_task_queue_factory.h"
+#include "media/engine/webrtc_media_engine.h"
+#include "api/audio_codecs/audio_encoder_factory_template.h"
+#include "api/audio_codecs/audio_decoder_factory_template.h"
+#include "api/audio_codecs/opus/audio_decoder_opus.h"
+#include "api/audio_codecs/opus/audio_decoder_multi_channel_opus.h"
+#include "api/audio_codecs/opus/audio_encoder_opus.h"
+#include "api/audio_codecs/L16/audio_decoder_L16.h"
+#include "api/audio_codecs/L16/audio_encoder_L16.h"
+
+#include "StaticThreads.h"
+#include "FakeAudioDeviceModule.h"
+#include "platform/PlatformInterface.h"
+
+#include "v2/ContentNegotiation.h"
+
+namespace {
+    class Context {
+    public:
+        Context(bool isOutgoing) :
+        _isOutgoing(isOutgoing),
+        _threads(tgcalls::StaticThreads::getThreads()),
+        _taskQueueFactory(webrtc::CreateDefaultTaskQueueFactory()),
+        _uniqueRandomIdGenerator(std::make_unique<rtc::UniqueRandomIdGenerator>()) {
+            _threads->getWorkerThread()->Invoke<void>(RTC_FROM_HERE, [&]() {
+                cricket::MediaEngineDependencies mediaDeps;
+                mediaDeps.task_queue_factory = _taskQueueFactory.get();
+                mediaDeps.audio_encoder_factory = webrtc::CreateAudioEncoderFactory<webrtc::AudioEncoderOpus, webrtc::AudioEncoderL16>();
+                mediaDeps.audio_decoder_factory = webrtc::CreateAudioDecoderFactory<webrtc::AudioDecoderOpus, webrtc::AudioDecoderL16>();
+
+                mediaDeps.video_encoder_factory = tgcalls::PlatformInterface::SharedInstance()->makeVideoEncoderFactory(true);
+                mediaDeps.video_decoder_factory = tgcalls::PlatformInterface::SharedInstance()->makeVideoDecoderFactory();
+
+                tgcalls::FakeAudioDeviceModule::Options options;
+                options.num_channels = 1;
+                _audioDeviceModule = tgcalls::FakeAudioDeviceModule::Creator(nullptr, nullptr, options)(_taskQueueFactory.get());
+                
+                mediaDeps.adm = _audioDeviceModule;
+
+                _mediaEngine = cricket::CreateMediaEngine(std::move(mediaDeps));
+
+                _channelManager = cricket::ChannelManager::Create(
+                    std::move(_mediaEngine),
+                    true,
+                    _threads->getWorkerThread(),
+                    _threads->getNetworkThread()
+                );
+            });
+
+            _contentNegotiationContext = std::make_unique<tgcalls::ContentNegotiationContext>(isOutgoing, _uniqueRandomIdGenerator.get());
+            _contentNegotiationContext->copyCodecsFromChannelManager(_channelManager.get(), isOutgoing);
+        }
+
+        ~Context() {
+            _contentNegotiationContext.reset();
+            
+            _threads->getWorkerThread()->Invoke<void>(RTC_FROM_HERE, [&]() {
+                _channelManager.reset();
+                _mediaEngine.reset();
+                _audioDeviceModule = nullptr;
+            });
+        }
+
+
+    public:
+        tgcalls::ContentNegotiationContext *contentNegotiationContext() const {
+            return _contentNegotiationContext.get();
+        }
+        
+        void assertSsrcs(std::vector<uint32_t> const &outgoingSsrcs, std::vector<uint32_t> const &incomingSsrcs) {
+            std::set<uint32_t> incomingSsrcsSet;
+            for (auto ssrc : incomingSsrcs) {
+                incomingSsrcsSet.insert(ssrc);
+            }
+            
+            std::set<uint32_t> outgoingSsrcsSet;
+            for (auto ssrc : outgoingSsrcs) {
+                outgoingSsrcsSet.insert(ssrc);
+            }
+            
+            std::set<uint32_t> actualIncomingSsrcs;
+            std::set<uint32_t> actualOutgoingSsrcs;
+            
+            auto coordinatedState = _contentNegotiationContext->coordinatedState();
+            XCTAssert(coordinatedState != nullptr);
+            
+            for (const auto &content : coordinatedState->incomingContents) {
+                actualIncomingSsrcs.insert(content.ssrc);
+            }
+            for (const auto &content : coordinatedState->outgoingContents) {
+                actualOutgoingSsrcs.insert(content.ssrc);
+            }
+            
+            XCTAssert(incomingSsrcsSet == actualIncomingSsrcs);
+            XCTAssert(outgoingSsrcsSet == actualOutgoingSsrcs);
+        }
+        
+        bool isContentsEqualToRemote(Context &remoteContext) {
+            auto localCoordinatedState = _contentNegotiationContext->coordinatedState();
+            auto remoteCoordinatedState = remoteContext.contentNegotiationContext()->coordinatedState();
+            
+            auto mediaContentComparator = [](tgcalls::signaling::MediaContent const &lhs, tgcalls::signaling::MediaContent const &rhs) -> bool {
+                return lhs.ssrc < rhs.ssrc;
+            };
+            
+            auto localIncomingContents = localCoordinatedState->incomingContents;
+            std::sort(localIncomingContents.begin(), localIncomingContents.end(), mediaContentComparator);
+            
+            auto localOutgoingContents = localCoordinatedState->outgoingContents;
+            std::sort(localOutgoingContents.begin(), localOutgoingContents.end(), mediaContentComparator);
+            
+            auto remoteIncomingContents = remoteCoordinatedState->incomingContents;
+            std::sort(remoteIncomingContents.begin(), remoteIncomingContents.end(), mediaContentComparator);
+            
+            auto remoteOutgoingContents = remoteCoordinatedState->outgoingContents;
+            std::sort(remoteOutgoingContents.begin(), remoteOutgoingContents.end(), mediaContentComparator);
+            
+            if (localIncomingContents != remoteOutgoingContents) {
+                return false;
+            }
+            if (localOutgoingContents != remoteIncomingContents) {
+                return false;
+            }
+            
+            return true;
+        }
+
+    private:
+        __unused bool _isOutgoing = false;
+        std::shared_ptr<tgcalls::Threads> _threads;
+        std::unique_ptr<webrtc::TaskQueueFactory> _taskQueueFactory;
+        std::unique_ptr<rtc::UniqueRandomIdGenerator> _uniqueRandomIdGenerator;
+        rtc::scoped_refptr<webrtc::AudioDeviceModule> _audioDeviceModule;
+        std::unique_ptr<cricket::MediaEngineInterface> _mediaEngine;
+        std::unique_ptr<cricket::ChannelManager> _channelManager;
+        std::unique_ptr<tgcalls::ContentNegotiationContext> _contentNegotiationContext;
+    };
+
+std::unique_ptr<tgcalls::ContentNegotiationContext::NegotiationContents> copyNegotiationContents(tgcalls::ContentNegotiationContext::NegotiationContents *value) {
+    if (!value) {
+        return nullptr;
+    }
+
+    auto result = std::make_unique<tgcalls::ContentNegotiationContext::NegotiationContents>();
+    result->exchangeId = value->exchangeId;
+    result->contents = value->contents;
+
+    return result;
+}
+
+void runUntilStableSequential(Context &localContext, Context &remoteContext) {
+    for (int i = 0; i < 6; i++) {
+        auto localOffer = localContext.contentNegotiationContext()->getPendingOffer();
+        if (localOffer) {
+            auto remoteAnswer = remoteContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(localOffer.get()));
+            XCTAssert(remoteAnswer != nullptr);
+            
+            auto localResponse = localContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(remoteAnswer.get()));
+            XCTAssert(localResponse == nullptr);
+        } else {
+            auto remoteOffer = remoteContext.contentNegotiationContext()->getPendingOffer();
+            if (remoteOffer) {
+                auto localAnswer = localContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(remoteOffer.get()));
+                XCTAssert(localAnswer != nullptr);
+                
+                auto remoteResponse = remoteContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(localAnswer.get()));
+                XCTAssert(remoteResponse == nullptr);
+            } else {
+                return;
+            }
+        }
+    }
+    
+    XCTFail(@"Did not complete");
+}
+
+void runUntilStableConcurrent(Context &localContext, Context &remoteContext) {
+    std::vector<std::unique_ptr<tgcalls::ContentNegotiationContext::NegotiationContents>> localNegotiationContent;
+    std::vector<std::unique_ptr<tgcalls::ContentNegotiationContext::NegotiationContents>> remoteNegotiationContent;
+    
+    for (int i = 0; i < 6; i++) {
+        std::unique_ptr<tgcalls::ContentNegotiationContext::NegotiationContents> nextLocalNegotiationContent;
+        std::unique_ptr<tgcalls::ContentNegotiationContext::NegotiationContents> nextRemoteNegotiationContent;
+        
+        while (!localNegotiationContent.empty()) {
+            auto content = std::move(localNegotiationContent[0]);
+            localNegotiationContent.erase(localNegotiationContent.begin());
+            
+            nextRemoteNegotiationContent = remoteContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(content.get()));
+        }
+        while (!remoteNegotiationContent.empty()) {
+            auto content = std::move(remoteNegotiationContent[0]);
+            remoteNegotiationContent.erase(remoteNegotiationContent.begin());
+            
+            nextLocalNegotiationContent = localContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(content.get()));
+        }
+        
+        if (nextLocalNegotiationContent) {
+            localNegotiationContent.push_back(std::move(nextLocalNegotiationContent));
+        }
+        if (nextRemoteNegotiationContent) {
+            remoteNegotiationContent.push_back(std::move(nextRemoteNegotiationContent));
+        }
+        
+        auto localOffer = localContext.contentNegotiationContext()->getPendingOffer();
+        if (localOffer) {
+            localNegotiationContent.push_back(std::move(localOffer));
+        }
+        
+        auto remoteOffer = remoteContext.contentNegotiationContext()->getPendingOffer();
+        if (remoteOffer) {
+            remoteNegotiationContent.push_back(std::move(remoteOffer));
+        }
+        
+        if (localNegotiationContent.empty() && remoteNegotiationContent.empty()) {
+            return;
+        }
+    }
+    
+    XCTFail(@"Did not complete");
+}
+
+}
+ 
+@interface NegotiationTests : XCTestCase
+@end
+ 
+@implementation NegotiationTests
+ 
+- (void)setUp {
+    [super setUp];
+    
+    self.continueAfterFailure = false;
+}
+ 
+- (void)tearDown {
+    [super tearDown];
+}
+
+- (void)testNegotiateEmpty {
+    Context localContext(true);
+    Context remoteContext(false);
+
+    XCTAssert(localContext.contentNegotiationContext()->getPendingOffer() != nullptr);
+    XCTAssert(remoteContext.contentNegotiationContext()->getPendingOffer() != nullptr);
+}
+ 
+- (void)testNegotiateAudioOnewayOutgoing {
+    Context localContext(true);
+    Context remoteContext(false);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    localContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Audio);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    auto offer = localContext.contentNegotiationContext()->getPendingOffer();
+    XCTAssert(offer != nullptr);
+    XCTAssert(offer->contents.size() == 1);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    XCTAssert(localContext.contentNegotiationContext()->getPendingOffer() == nullptr);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    auto response = remoteContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(offer.get()));
+    XCTAssert(response != nullptr);
+    XCTAssert(response->contents.size() == offer->contents.size());
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.size() == 1);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents[0].ssrc == offer->contents[0].ssrc);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    auto backOffer = remoteContext.contentNegotiationContext()->getPendingOffer();
+    XCTAssert(backOffer != nullptr);
+    XCTAssert(backOffer->contents.size() == 0);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.size() == 1);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents[0].ssrc == offer->contents[0].ssrc);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    auto responseToAnswer = localContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(response.get()));
+    XCTAssert(responseToAnswer == nullptr);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.size() == 1);
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents[0].ssrc == offer->contents[0].ssrc);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.size() == 1);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents[0].ssrc == offer->contents[0].ssrc);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    auto nextOffer = localContext.contentNegotiationContext()->getPendingOffer();
+    XCTAssert(nextOffer == nullptr);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.size() == 1);
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents[0].ssrc == offer->contents[0].ssrc);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.size() == 1);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents[0].ssrc == offer->contents[0].ssrc);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+}
+
+- (void)testNegotiateAudioOnewayIncoming {
+    Context localContext(true);
+    Context remoteContext(false);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    remoteContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Audio);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    auto offer = localContext.contentNegotiationContext()->getPendingOffer();
+    XCTAssert(offer != nullptr);
+    XCTAssert(offer->contents.empty());
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    XCTAssert(localContext.contentNegotiationContext()->getPendingOffer() == nullptr);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    auto response = remoteContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(offer.get()));
+    XCTAssert(response != nullptr);
+    XCTAssert(response->contents.size() == offer->contents.size());
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    auto backOffer = remoteContext.contentNegotiationContext()->getPendingOffer();
+    XCTAssert(backOffer != nullptr);
+    XCTAssert(backOffer->contents.size() == 1);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    auto responseToAnswer = localContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(response.get()));
+    XCTAssert(responseToAnswer == nullptr);
+    
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    
+    auto responseToBackOffer = localContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(backOffer.get()));
+    XCTAssert(responseToBackOffer != nullptr);
+    XCTAssert(responseToBackOffer->contents.size() == 1);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.size() == 1);
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents[0].ssrc == backOffer->contents[0].ssrc);
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    
+    auto responseToBackOfferAnswer = remoteContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(responseToBackOffer.get()));
+    XCTAssert(responseToBackOfferAnswer == nullptr);
+
+    XCTAssert(localContext.contentNegotiationContext()->getPendingOffer() == nullptr);
+    XCTAssert(remoteContext.contentNegotiationContext()->getPendingOffer() == nullptr);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.size() == 1);
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents[0].ssrc == backOffer->contents[0].ssrc);
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.size() == 1);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents[0].ssrc == backOffer->contents[0].ssrc);
+}
+
+- (void)testNegotiateAudioTwoway {
+    Context localContext(true);
+    Context remoteContext(false);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    localContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Audio);
+    remoteContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Audio);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    auto offer = localContext.contentNegotiationContext()->getPendingOffer();
+    XCTAssert(offer != nullptr);
+    XCTAssert(offer->contents.size() == 1);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    XCTAssert(localContext.contentNegotiationContext()->getPendingOffer() == nullptr);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    auto response = remoteContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(offer.get()));
+    XCTAssert(response != nullptr);
+    XCTAssert(response->contents.size() == offer->contents.size());
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.size() == 1);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents[0].ssrc == offer->contents[0].ssrc);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    auto backOffer = remoteContext.contentNegotiationContext()->getPendingOffer();
+    XCTAssert(backOffer != nullptr);
+    XCTAssert(backOffer->contents.size() == 1);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.size() == 1);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents[0].ssrc == offer->contents[0].ssrc);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+
+    auto responseToAnswer = localContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(response.get()));
+    XCTAssert(responseToAnswer == nullptr);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.empty());
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.size() == 1);
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents[0].ssrc == offer->contents[0].ssrc);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.size() == 1);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents[0].ssrc == offer->contents[0].ssrc);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    
+    XCTAssert(localContext.contentNegotiationContext()->getPendingOffer() == nullptr);
+
+    auto responseToBackOffer = localContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(backOffer.get()));
+    XCTAssert(responseToBackOffer != nullptr);
+    XCTAssert(responseToBackOffer->contents.size() == 1);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.size() == 1);
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents[0].ssrc == backOffer->contents[0].ssrc);
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.size() == 1);
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents[0].ssrc == offer->contents[0].ssrc);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.size() == 1);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents[0].ssrc == offer->contents[0].ssrc);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.empty());
+    
+    auto responseToBackOfferAnswer = remoteContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(responseToBackOffer.get()));
+    XCTAssert(responseToBackOfferAnswer == nullptr);
+
+    XCTAssert(localContext.contentNegotiationContext()->getPendingOffer() == nullptr);
+    XCTAssert(remoteContext.contentNegotiationContext()->getPendingOffer() == nullptr);
+
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents.size() == 1);
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->incomingContents[0].ssrc == backOffer->contents[0].ssrc);
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents.size() == 1);
+    XCTAssert(localContext.contentNegotiationContext()->coordinatedState()->outgoingContents[0].ssrc == offer->contents[0].ssrc);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents.size() == 1);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->incomingContents[0].ssrc == offer->contents[0].ssrc);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents.size() == 1);
+    XCTAssert(remoteContext.contentNegotiationContext()->coordinatedState()->outgoingContents[0].ssrc == backOffer->contents[0].ssrc);
+}
+
+- (void)testConcurrentOffers {
+    Context localContext(true);
+    Context remoteContext(false);
+
+    auto localOffer = localContext.contentNegotiationContext()->getPendingOffer();
+    XCTAssert(localOffer != nullptr);
+    
+    auto remoteOffer = remoteContext.contentNegotiationContext()->getPendingOffer();
+    XCTAssert(remoteOffer != nullptr);
+    
+    auto localAnswer = remoteContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(localOffer.get()));
+    XCTAssert(localAnswer != nullptr);
+    XCTAssert(localAnswer->exchangeId == localOffer->exchangeId);
+    
+    auto remoteAnswer = localContext.contentNegotiationContext()->setRemoteNegotiationContent(copyNegotiationContents(remoteOffer.get()));
+    XCTAssert(remoteAnswer == nullptr);
+}
+
+- (void)service_runUntilStable1Using:(std::function<void(Context &localContext, Context &remoteContext)>)runUntilStable {
+    Context localContext(true);
+    Context remoteContext(false);
+    
+    runUntilStable(localContext, remoteContext);
+    
+    localContext.assertSsrcs({}, {});
+    remoteContext.assertSsrcs({}, {});
+    localContext.isContentsEqualToRemote(remoteContext);
+    
+    auto localAudioId = localContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Audio);
+    
+    runUntilStable(localContext, remoteContext);
+    
+    auto localAudioSsrc = localContext.contentNegotiationContext()->outgoingChannelSsrc(localAudioId);
+    XCTAssert(localAudioSsrc);
+    
+    localContext.assertSsrcs({ localAudioSsrc.value() }, {});
+    remoteContext.assertSsrcs({}, { localAudioSsrc.value() });
+    localContext.isContentsEqualToRemote(remoteContext);
+    
+    auto remoteAudioId = remoteContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Audio);
+    
+    runUntilStable(localContext, remoteContext);
+    
+    auto remoteAudioSsrc = remoteContext.contentNegotiationContext()->outgoingChannelSsrc(remoteAudioId);
+    XCTAssert(remoteAudioSsrc);
+    
+    localContext.assertSsrcs({ localAudioSsrc.value() }, { remoteAudioSsrc.value() });
+    remoteContext.assertSsrcs({ remoteAudioSsrc.value() }, { localAudioSsrc.value() });
+    localContext.isContentsEqualToRemote(remoteContext);
+    
+    auto remoteVideoId = remoteContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Video);
+    
+    runUntilStable(localContext, remoteContext);
+    
+    auto remoteVideoSsrc = remoteContext.contentNegotiationContext()->outgoingChannelSsrc(remoteVideoId);
+    XCTAssert(remoteVideoSsrc);
+    
+    localContext.assertSsrcs({ localAudioSsrc.value() }, { remoteAudioSsrc.value(), remoteVideoSsrc.value() });
+    remoteContext.assertSsrcs({ remoteAudioSsrc.value(), remoteVideoSsrc.value() }, { localAudioSsrc.value() });
+    localContext.isContentsEqualToRemote(remoteContext);
+    
+    auto localVideoId = localContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Video);
+    
+    runUntilStable(localContext, remoteContext);
+    
+    auto localVideoSsrc = localContext.contentNegotiationContext()->outgoingChannelSsrc(localVideoId);
+    XCTAssert(localVideoSsrc);
+    
+    localContext.assertSsrcs({ localAudioSsrc.value(), localVideoSsrc.value() }, { remoteAudioSsrc.value(), remoteVideoSsrc.value() });
+    remoteContext.assertSsrcs({ remoteAudioSsrc.value(), remoteVideoSsrc.value() }, { localAudioSsrc.value(), localVideoSsrc.value() });
+    localContext.isContentsEqualToRemote(remoteContext);
+    
+    auto remoteScreencastId = remoteContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Video);
+    
+    runUntilStable(localContext, remoteContext);
+    
+    auto remoteScreencastSsrc = remoteContext.contentNegotiationContext()->outgoingChannelSsrc(remoteScreencastId);
+    XCTAssert(remoteScreencastSsrc);
+    
+    localContext.assertSsrcs({ localAudioSsrc.value(), localVideoSsrc.value() }, { remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() });
+    remoteContext.assertSsrcs({ remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() }, { localAudioSsrc.value(), localVideoSsrc.value() });
+    localContext.isContentsEqualToRemote(remoteContext);
+    
+    localContext.contentNegotiationContext()->removeOutgoingChannel(localVideoId);
+    
+    // local removal is reflected right away
+    localContext.assertSsrcs({ localAudioSsrc.value() }, { remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() });
+    remoteContext.assertSsrcs({ remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() }, { localAudioSsrc.value(), localVideoSsrc.value() });
+    localVideoSsrc = localContext.contentNegotiationContext()->outgoingChannelSsrc(localVideoId);
+    XCTAssert(!localVideoSsrc);
+    
+    runUntilStable(localContext, remoteContext);
+    
+    localVideoSsrc = localContext.contentNegotiationContext()->outgoingChannelSsrc(localVideoId);
+    XCTAssert(!localVideoSsrc);
+    
+    localContext.assertSsrcs({ localAudioSsrc.value() }, { remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() });
+    remoteContext.assertSsrcs({ remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() }, { localAudioSsrc.value() });
+    localContext.isContentsEqualToRemote(remoteContext);
+    
+    localVideoId = localContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Video);
+    
+    runUntilStable(localContext, remoteContext);
+    
+    localVideoSsrc = localContext.contentNegotiationContext()->outgoingChannelSsrc(localVideoId);
+    XCTAssert(localVideoSsrc);
+    
+    localContext.assertSsrcs({ localAudioSsrc.value(), localVideoSsrc.value() }, { remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() });
+    remoteContext.assertSsrcs({ remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() }, { localAudioSsrc.value(), localVideoSsrc.value() });
+    localContext.isContentsEqualToRemote(remoteContext);
+}
+
+- (void)service_runUntilStable2Using:(std::function<void(Context &localContext, Context &remoteContext)>)runUntilStable {
+    Context localContext(true);
+    Context remoteContext(false);
+    
+    runUntilStable(localContext, remoteContext);
+    
+    localContext.assertSsrcs({}, {});
+    remoteContext.assertSsrcs({}, {});
+    localContext.isContentsEqualToRemote(remoteContext);
+    
+    auto localAudioId = localContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Audio);
+    auto remoteAudioId = remoteContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Audio);
+    
+    runUntilStable(localContext, remoteContext);
+    
+    auto localAudioSsrc = localContext.contentNegotiationContext()->outgoingChannelSsrc(localAudioId);
+    XCTAssert(localAudioSsrc);
+    
+    auto remoteAudioSsrc = remoteContext.contentNegotiationContext()->outgoingChannelSsrc(remoteAudioId);
+    XCTAssert(remoteAudioSsrc);
+    
+    localContext.assertSsrcs({ localAudioSsrc.value() }, { remoteAudioSsrc.value() });
+    remoteContext.assertSsrcs({ remoteAudioSsrc.value() }, { localAudioSsrc.value() });
+    localContext.isContentsEqualToRemote(remoteContext);
+    
+    auto remoteVideoId = remoteContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Video);
+    auto localVideoId = localContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Video);
+    
+    runUntilStable(localContext, remoteContext);
+    
+    auto remoteVideoSsrc = remoteContext.contentNegotiationContext()->outgoingChannelSsrc(remoteVideoId);
+    XCTAssert(remoteVideoSsrc);
+    
+    auto localVideoSsrc = localContext.contentNegotiationContext()->outgoingChannelSsrc(localVideoId);
+    XCTAssert(localVideoSsrc);
+    
+    localContext.assertSsrcs({ localAudioSsrc.value(), localVideoSsrc.value() }, { remoteAudioSsrc.value(), remoteVideoSsrc.value() });
+    remoteContext.assertSsrcs({ remoteAudioSsrc.value(), remoteVideoSsrc.value() }, { localAudioSsrc.value(), localVideoSsrc.value() });
+    localContext.isContentsEqualToRemote(remoteContext);
+    
+    auto remoteScreencastId = remoteContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Video);
+    
+    runUntilStable(localContext, remoteContext);
+    
+    auto remoteScreencastSsrc = remoteContext.contentNegotiationContext()->outgoingChannelSsrc(remoteScreencastId);
+    XCTAssert(remoteScreencastSsrc);
+    
+    localContext.assertSsrcs({ localAudioSsrc.value(), localVideoSsrc.value() }, { remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() });
+    remoteContext.assertSsrcs({ remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() }, { localAudioSsrc.value(), localVideoSsrc.value() });
+    localContext.isContentsEqualToRemote(remoteContext);
+    
+    localContext.contentNegotiationContext()->removeOutgoingChannel(localVideoId);
+    
+    // local removal is reflected right away
+    localContext.assertSsrcs({ localAudioSsrc.value() }, { remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() });
+    remoteContext.assertSsrcs({ remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() }, { localAudioSsrc.value(), localVideoSsrc.value() });
+    localVideoSsrc = localContext.contentNegotiationContext()->outgoingChannelSsrc(localVideoId);
+    XCTAssert(!localVideoSsrc);
+    
+    runUntilStable(localContext, remoteContext);
+    
+    localVideoSsrc = localContext.contentNegotiationContext()->outgoingChannelSsrc(localVideoId);
+    XCTAssert(!localVideoSsrc);
+    
+    localContext.assertSsrcs({ localAudioSsrc.value() }, { remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() });
+    remoteContext.assertSsrcs({ remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() }, { localAudioSsrc.value() });
+    localContext.isContentsEqualToRemote(remoteContext);
+    
+    localVideoId = localContext.contentNegotiationContext()->addOutgoingChannel(tgcalls::signaling::MediaContent::Type::Video);
+    
+    runUntilStable(localContext, remoteContext);
+    
+    localVideoSsrc = localContext.contentNegotiationContext()->outgoingChannelSsrc(localVideoId);
+    XCTAssert(localVideoSsrc);
+    
+    localContext.assertSsrcs({ localAudioSsrc.value(), localVideoSsrc.value() }, { remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() });
+    remoteContext.assertSsrcs({ remoteAudioSsrc.value(), remoteVideoSsrc.value(), remoteScreencastSsrc.value() }, { localAudioSsrc.value(), localVideoSsrc.value() });
+    localContext.isContentsEqualToRemote(remoteContext);
+}
+- (void)testConvergenceSequential1 {
+    [self service_runUntilStable1Using:&runUntilStableSequential];
+}
+
+- (void)testConvergenceSequential2 {
+    [self service_runUntilStable2Using:&runUntilStableSequential];
+}
+
+- (void)testConvergenceConcurrent1 {
+    [self service_runUntilStable1Using:&runUntilStableConcurrent];
+}
+
+- (void)testConvergenceConcurrent2 {
+    [self service_runUntilStable2Using:&runUntilStableConcurrent];
+}
+
+@end
diff --git a/submodules/TgVoipWebrtc/tgcalls b/submodules/TgVoipWebrtc/tgcalls
index 33af020811..95369c01df 160000
--- a/submodules/TgVoipWebrtc/tgcalls
+++ b/submodules/TgVoipWebrtc/tgcalls
@@ -1 +1 @@
-Subproject commit 33af0208111e5994e33c7fbb8872cd08bf38edd7
+Subproject commit 95369c01dfc8639b89dd91c4bc6e9da2ae2ed223