iOS Audio not working during call answered when phone is locked. WebRTC used for calling

user_299610 0
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I am facing a problem with Audio When using Callkit with WebRTC for VOIP call, While answering the call from Lock Screen.

General Functionality :

My app activates the audioSession when it's launched. For an incoming call, SDP Offer & Answer are generated and exchanged. Peer Connection is set up. Both audio and video streams are generated, whether it's audio call or video call. Then Call is reported to callkit by using the following code:

    callProvider.reportNewIncomingCall(with: currentCallUUID!, update: update) { error in }

If app is in the foreground, it works fine.

But, when the phone is locked, and user answers the call from lock screen, the Streams are exchanged but no audio comes on either end until user enters into the app himself.

As the user enters into the App, audio becomes active on both the ends.

All the background settings and capabilities are set properly.

I have also referred to the following work around provided by Apple staff. But even it does not work.

https://forums.developer.apple.com/thread/64544

As I mentioned, I am using WebRTC for calling. If I exchange the media streams after the user answers the call( still on Lock Screen) and peer connection is set at that time. It works fine (But it adds the delay in making the call connection).

But if Peer Connection is made before displaying call (say before reporting call to callkit), the audio stops working.

callkit webrtc voip audio ios
3 Answers

Please Note that I share my code and its about to my needs and I share for reference. you need to change it according to your need.

when you receive voip notification create new incident of your webrtc handling class, and add this two lines to code block because enabling audio session from voip notification fails

RTCAudioSession.sharedInstance().useManualAudio = true
RTCAudioSession.sharedInstance().isAudioEnabled = false

didReceive method;

func pushRegistry(_ registry: PKPushRegistry, didReceiveIncomingPushWith payload: PKPushPayload, for type: PKPushType, completion: @escaping () -> Void) {
               let state = UIApplication.shared.applicationState
               
        
     
                   if(payload.dictionaryPayload["hangup"] == nil && state != .active
                   ){
                       
               
                     Globals.voipPayload = payload.dictionaryPayload as! [String:Any] // I pass parameters to Webrtc handler via Global singleton to create answer according to sdp sent by payload.
                        
                       RTCAudioSession.sharedInstance().useManualAudio = true
                       RTCAudioSession.sharedInstance().isAudioEnabled = false
                       
                     
                      
                     Globals.sipGateway = SipGateway() // my Webrtc and Janus gateway handler class
                    
                       
                     Globals.sipGateway?.configureCredentials(true) // I check janus gateway credentials stored in Shared preferences and initiate websocket connection and create peerconnection 
to my janus gateway which is signaling server for my environment
                    
                       
                  initProvider() //Crating callkit provider
                       
                       self.update.remoteHandle = CXHandle(type: .generic, value:String(describing: payload.dictionaryPayload["caller_id"]!))
                          Globals.callId = UUID()
             
                       let state = UIApplication.shared.applicationState
                       
                      
                          Globals.provider.reportNewIncomingCall(with:Globals.callId , update: self.update, completion: { error in
                           
                           
                          })
                       
                
               }
              
           }
    
        
        func  initProvider(){
            let config = CXProviderConfiguration(localizedName: "ulakBEL")
            config.iconTemplateImageData = UIImage(named: "ulakbel")!.pngData()
            config.ringtoneSound = "ringtone.caf"
                   // config.includesCallsInRecents = false;
                    config.supportsVideo = false
            
            Globals.provider = CXProvider(configuration:config )
            Globals.provider.setDelegate(self, queue: nil)
             update = CXCallUpdate()
             update.hasVideo = false
             update.supportsDTMF = true
      
        }

modify your didActivate and didDeActive delegate functions like below,

func provider(_ provider: CXProvider, didActivate audioSession: AVAudioSession) {
       print("CallManager didActivate")
       RTCAudioSession.sharedInstance().audioSessionDidActivate(audioSession)
       RTCAudioSession.sharedInstance().isAudioEnabled = true
      // self.callDelegate?.callIsAnswered()
    
 
   }

   func provider(_ provider: CXProvider, didDeactivate audioSession: AVAudioSession) {
       print("CallManager didDeactivate")
RTCAudioSession.sharedInstance().audioSessionDidDeactivate(audioSession)
       RTCAudioSession.sharedInstance().isAudioEnabled = false
    
 
   }

in Webrtc handler class configure media senders and audiosession

private func createPeerConnection(webRTCCallbacks:PluginHandleWebRTCCallbacksDelegate) {
   
        let rtcConfig =  RTCConfiguration.init()
        rtcConfig.iceServers = server.iceServers
        rtcConfig.bundlePolicy = RTCBundlePolicy.maxBundle
        rtcConfig.rtcpMuxPolicy = RTCRtcpMuxPolicy.require
        rtcConfig.continualGatheringPolicy = .gatherContinually
        rtcConfig.sdpSemantics = .planB
        
        let constraints = RTCMediaConstraints(mandatoryConstraints: nil,
                                                 optionalConstraints: ["DtlsSrtpKeyAgreement":kRTCMediaConstraintsValueTrue])
           
        pc = sessionFactory.peerConnection(with: rtcConfig, constraints: constraints, delegate: nil)
        self.createMediaSenders()
        self.configureAudioSession()
        
   
        
      if webRTCCallbacks.getJsep() != nil{
        handleRemoteJsep(webrtcCallbacks: webRTCCallbacks)
        }
      
    }

mediaSenders;

private func createMediaSenders() {
        let streamId = "stream"
        
        // Audio
        let audioTrack = self.createAudioTrack()
        self.pc.add(audioTrack, streamIds: [streamId])
        
        // Video
      /*  let videoTrack = self.createVideoTrack()
        self.localVideoTrack = videoTrack
        self.peerConnection.add(videoTrack, streamIds: [streamId])
        self.remoteVideoTrack = self.peerConnection.transceivers.first { $0.mediaType == .video }?.receiver.track as? RTCVideoTrack
        
        // Data
        if let dataChannel = createDataChannel() {
            dataChannel.delegate = self
            self.localDataChannel = dataChannel
        }*/
    }

  private func createAudioTrack() -> RTCAudioTrack {
        let audioConstrains = RTCMediaConstraints(mandatoryConstraints: nil, optionalConstraints: nil)
        let audioSource = sessionFactory.audioSource(with: audioConstrains)
        let audioTrack = sessionFactory.audioTrack(with: audioSource, trackId: "audio0")
        return audioTrack
    }

audioSession ;

private func configureAudioSession() {
        self.rtcAudioSession.lockForConfiguration()
        do {
            try self.rtcAudioSession.setCategory(AVAudioSession.Category.playAndRecord.rawValue)
            try self.rtcAudioSession.setMode(AVAudioSession.Mode.voiceChat.rawValue)
        } catch let error {
            debugPrint("Error changeing AVAudioSession category: \(error)")
        }
        self.rtcAudioSession.unlockForConfiguration()
    }

Please consider that because I worked with callbacks and delegates code includes delegates and callback chunks. you can ignore them accordingly!!

FOR REFERENCE You can also check the example at this link

user_93468590
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