diff --git a/spec/unit/webrtc/call.spec.ts b/spec/unit/webrtc/call.spec.ts
index 9e12db20f4..55bb3f2278 100644
--- a/spec/unit/webrtc/call.spec.ts
+++ b/spec/unit/webrtc/call.spec.ts
@@ -145,6 +145,14 @@ describe('Call', function() {
         client.client.mediaHandler = new MockMediaHandler;
         client.client.getMediaHandler = () => client.client.mediaHandler;
         client.httpBackend.when("GET", "/voip/turnServer").respond(200, {});
+        client.client.getRoom = () => {
+            return {
+                getMember: () => {
+                    return {};
+                },
+            };
+        };
+
         call = new MatrixCall({
             client: client.client,
             roomId: '!foo:bar',
@@ -175,6 +183,7 @@ describe('Call', function() {
                     },
                 };
             },
+            getSender: () => "@test:foo",
         });
 
         call.peerConn.addIceCandidate = jest.fn();
@@ -192,6 +201,7 @@ describe('Call', function() {
                     ],
                 };
             },
+            getSender: () => "@test:foo",
         });
         expect(call.peerConn.addIceCandidate.mock.calls.length).toBe(1);
 
@@ -209,6 +219,7 @@ describe('Call', function() {
                     ],
                 };
             },
+            getSender: () => "@test:foo",
         });
         expect(call.peerConn.addIceCandidate.mock.calls.length).toBe(1);
 
@@ -236,6 +247,7 @@ describe('Call', function() {
                     ],
                 };
             },
+            getSender: () => "@test:foo",
         });
 
         call.onRemoteIceCandidatesReceived({
@@ -252,6 +264,7 @@ describe('Call', function() {
                     ],
                 };
             },
+            getSender: () => "@test:foo",
         });
 
         expect(call.peerConn.addIceCandidate.mock.calls.length).toBe(0);
@@ -267,6 +280,7 @@ describe('Call', function() {
                     },
                 };
             },
+            getSender: () => "@test:foo",
         });
 
         expect(call.peerConn.addIceCandidate.mock.calls.length).toBe(1);
@@ -291,6 +305,7 @@ describe('Call', function() {
                     },
                 };
             },
+            getSender: () => "@test:foo",
         });
 
         const identChangedCallback = jest.fn();
@@ -308,6 +323,7 @@ describe('Call', function() {
                     },
                 };
             },
+            getSender: () => "@test:foo",
         });
 
         expect(identChangedCallback).toHaveBeenCalled();
@@ -347,6 +363,7 @@ describe('Call', function() {
                     },
                 };
             },
+            getSender: () => "@test:foo",
         });
 
         call.pushRemoteFeed(new MockMediaStream("remote_stream"));
@@ -376,6 +393,7 @@ describe('Call', function() {
                     },
                 };
             },
+            getSender: () => "@test:foo",
         });
 
         call.setScreensharingEnabledWithoutMetadataSupport = jest.fn();
diff --git a/src/client.ts b/src/client.ts
index 0885554872..3ce67168ce 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -1322,6 +1322,7 @@ export class MatrixClient extends EventEmitter {
     public async createGroupCall(
         roomId: string,
         type: GroupCallType,
+        isPtt: boolean,
         intent: GroupCallIntent,
         dataChannelsEnabled?: boolean,
         dataChannelOptions?: IGroupCallDataChannelOptions,
@@ -1340,6 +1341,7 @@ export class MatrixClient extends EventEmitter {
             this,
             room,
             type,
+            isPtt,
             intent,
             undefined,
             dataChannelsEnabled,
diff --git a/src/webrtc/groupCall.ts b/src/webrtc/groupCall.ts
index 45ccb6099c..32f6fa2955 100644
--- a/src/webrtc/groupCall.ts
+++ b/src/webrtc/groupCall.ts
@@ -59,6 +59,12 @@ export class GroupCallError extends Error {
     }
 }
 
+export class OtherUserSpeakingError extends Error {
+    constructor() {
+        super("Cannot unmute: another user is speaking");
+    }
+}
+
 export interface IGroupCallDataChannelOptions {
     ordered: boolean;
     maxPacketLifeTime: number;
@@ -112,6 +118,7 @@ export class GroupCall extends EventEmitter {
     public activeSpeakerInterval = 1000;
     public retryCallInterval = 5000;
     public participantTimeout = 1000 * 15;
+    public pttMaxTransmitTime = 1000 * 20;
 
     public state = GroupCallState.LocalCallFeedUninitialized;
     public activeSpeaker?: string; // userId
@@ -129,11 +136,13 @@ export class GroupCall extends EventEmitter {
     private retryCallLoopTimeout?: number;
     private retryCallCounts: Map<string, number> = new Map();
     private reEmitter: ReEmitter;
+    private transmitTimer: number | null = null;
 
     constructor(
         private client: MatrixClient,
         public room: Room,
         public type: GroupCallType,
+        public isPtt: boolean,
         public intent: GroupCallIntent,
         groupCallId?: string,
         private dataChannelsEnabled?: boolean,
@@ -160,6 +169,7 @@ export class GroupCall extends EventEmitter {
             {
                 "m.intent": this.intent,
                 "m.type": this.type,
+                "io.element.ptt": this.isPtt,
                 // TODO: Specify datachannels
                 "dataChannelsEnabled": this.dataChannelsEnabled,
                 "dataChannelOptions": this.dataChannelOptions,
@@ -208,6 +218,11 @@ export class GroupCall extends EventEmitter {
             throw error;
         }
 
+        // start muted on ptt calls
+        if (this.isPtt) {
+            setTracksEnabled(stream.getAudioTracks(), false);
+        }
+
         const userId = this.client.getUserId();
 
         const callFeed = new CallFeed({
@@ -216,7 +231,7 @@ export class GroupCall extends EventEmitter {
             userId,
             stream,
             purpose: SDPStreamMetadataPurpose.Usermedia,
-            audioMuted: stream.getAudioTracks().length === 0,
+            audioMuted: stream.getAudioTracks().length === 0 || this.isPtt,
             videoMuted: stream.getVideoTracks().length === 0,
         });
 
@@ -318,10 +333,20 @@ export class GroupCall extends EventEmitter {
         this.retryCallCounts.clear();
         clearTimeout(this.retryCallLoopTimeout);
 
+        if (this.transmitTimer !== null) {
+            clearTimeout(this.transmitTimer);
+            this.transmitTimer = null;
+        }
+
         this.client.removeListener("Call.incoming", this.onIncomingCall);
     }
 
     public leave() {
+        if (this.transmitTimer !== null) {
+            clearTimeout(this.transmitTimer);
+            this.transmitTimer = null;
+        }
+
         this.dispose();
         this.setState(GroupCallState.LocalCallFeedUninitialized);
     }
@@ -329,6 +354,11 @@ export class GroupCall extends EventEmitter {
     public async terminate(emitStateEvent = true) {
         this.dispose();
 
+        if (this.transmitTimer !== null) {
+            clearTimeout(this.transmitTimer);
+            this.transmitTimer = null;
+        }
+
         this.participants = [];
         this.client.removeListener(
             "RoomState.members",
@@ -382,6 +412,24 @@ export class GroupCall extends EventEmitter {
             return false;
         }
 
+        // set a timer for the maximum transmit time on PTT calls
+        if (this.isPtt) {
+            // if anoher user is currently unmuted, we can't unmute
+            if (!muted && this.userMediaFeeds.some(f => !f.isAudioMuted())) {
+                throw new OtherUserSpeakingError();
+            }
+
+            // Set or clear the max transmit timer
+            if (!muted && this.isMicrophoneMuted()) {
+                this.transmitTimer = setTimeout(() => {
+                    this.setMicrophoneMuted(true);
+                }, this.pttMaxTransmitTime);
+            } else if (muted && !this.isMicrophoneMuted()) {
+                clearTimeout(this.transmitTimer);
+                this.transmitTimer = null;
+            }
+        }
+
         if (this.localCallFeed) {
             logger.log(`groupCall ${this.groupCallId} setMicrophoneMuted stream ${
                 this.localCallFeed.stream.id} muted ${muted}`);
diff --git a/src/webrtc/groupCallEventHandler.ts b/src/webrtc/groupCallEventHandler.ts
index 99e726f1f1..476d0acfab 100644
--- a/src/webrtc/groupCallEventHandler.ts
+++ b/src/webrtc/groupCallEventHandler.ts
@@ -93,6 +93,8 @@ export class GroupCallEventHandler {
             return;
         }
 
+        const isPtt = Boolean(content["io.element.ptt"]);
+
         let dataChannelOptions: IGroupCallDataChannelOptions | undefined;
 
         if (content?.dataChannelsEnabled && content?.dataChannelOptions) {
@@ -105,6 +107,7 @@ export class GroupCallEventHandler {
             this.client,
             room,
             callType,
+            isPtt,
             callIntent,
             groupCallId,
             content?.dataChannelsEnabled,