diff --git a/src/matrix/calls/CallHandler.ts b/src/matrix/calls/CallHandler.ts
index 2ed8bf87..c33f24eb 100644
--- a/src/matrix/calls/CallHandler.ts
+++ b/src/matrix/calls/CallHandler.ts
@@ -201,11 +201,12 @@ export class CallHandler {
     private handleCallMemberEvent(event: StateEvent, log: ILogItem) {
         const userId = event.state_key;
         const calls = event.content["m.calls"] ?? [];
+        const eventTimestamp = event.origin_server_ts;
         for (const call of calls) {
             const callId = call["m.call_id"];
             const groupCall = this._calls.get(callId);
             // TODO: also check the member when receiving the m.call event
-            groupCall?.updateMembership(userId, call, log);
+            groupCall?.updateMembership(userId, call, eventTimestamp, log);
         };
         const newCallIdsMemberOf = new Set<string>(calls.map(call => call["m.call_id"]));
         let previousCallIdsMemberOf = this.memberToCallIds.get(userId);
diff --git a/src/matrix/calls/group/GroupCall.ts b/src/matrix/calls/group/GroupCall.ts
index a05ebe87..dc48a692 100644
--- a/src/matrix/calls/group/GroupCall.ts
+++ b/src/matrix/calls/group/GroupCall.ts
@@ -64,6 +64,9 @@ export class GroupCall extends EventEmitter<{change: never}> {
     private _memberOptions: MemberOptions;
     private _state: GroupCallState;
 
+    private _deviceIndex?: number;
+    private _eventTimestamp?: number;
+
     constructor(
         public readonly id: string,
         newCall: boolean,
@@ -103,6 +106,14 @@ export class GroupCall extends EventEmitter<{change: never}> {
         return this.callContent?.["m.intent"];
     }
 
+    get deviceIndex(): number | undefined {
+        return this._deviceIndex;
+    }
+
+    get eventTimestamp(): number | undefined {
+        return this._eventTimestamp;
+    }
+
     join(localMedia: LocalMedia): Promise<void> {
         return this.logItem.wrap("join", async log => {
             if (this._state !== GroupCallState.Created) {
@@ -188,16 +199,21 @@ export class GroupCall extends EventEmitter<{change: never}> {
     }
 
     /** @internal */
-    updateMembership(userId: string, callMembership: CallMembership, syncLog: ILogItem) {
+    updateMembership(userId: string, callMembership: CallMembership, eventTimestamp: number, syncLog: ILogItem) {
         this.logItem.wrap({l: "updateMember", id: userId}, log => {
             syncLog.refDetached(log);
             const devices = callMembership["m.devices"];
             const previousDeviceIds = this.getDeviceIdsForUserId(userId);
-            for (const device of devices) {
+            for (let deviceIndex = 0; deviceIndex < devices.length; deviceIndex++) {
+                const device = devices[deviceIndex];
                 const deviceId = device.device_id;
                 const memberKey = getMemberKey(userId, deviceId);
                 log.wrap({l: "update device member", id: memberKey}, log => {
                     if (userId === this.options.ownUserId && deviceId === this.options.ownDeviceId) {
+
+                        this._deviceIndex = deviceIndex;
+                        this._eventTimestamp = eventTimestamp;
+
                         if (this._state === GroupCallState.Joining) {
                             log.set("update_own", true);
                             this._state = GroupCallState.Joined;
@@ -207,14 +223,14 @@ export class GroupCall extends EventEmitter<{change: never}> {
                         let member = this._members.get(memberKey);
                         if (member) {
                             log.set("update", true);
-                            member!.updateCallInfo(device);
+                            member!.updateCallInfo(device, deviceIndex, eventTimestamp);
                         } else {
                             const logItem = this.logItem.child({l: "member", id: memberKey});
                             log.set("add", true);
                             log.refDetached(logItem);
                             member = new Member(
                                 RoomMember.fromUserId(this.roomId, userId, "join"),
-                                device, this._memberOptions, logItem
+                                device, deviceIndex, eventTimestamp, this._memberOptions, logItem
                             );
                             this._members.add(memberKey, member);
                             if (this._state === GroupCallState.Joining || this._state === GroupCallState.Joined) {
@@ -332,6 +348,10 @@ export class GroupCall extends EventEmitter<{change: never}> {
             ["session_id"]: this.options.sessionId,
             feeds: [{purpose: "m.usermedia"}]
         });
+
+        this._deviceIndex = callInfo["m.devices"].length;
+        this._eventTimestamp = Date.now();
+
         return stateContent;
     }
 
diff --git a/src/matrix/calls/group/Member.ts b/src/matrix/calls/group/Member.ts
index 06693030..7e6281aa 100644
--- a/src/matrix/calls/group/Member.ts
+++ b/src/matrix/calls/group/Member.ts
@@ -55,6 +55,8 @@ export class Member {
     constructor(
         public readonly member: RoomMember,
         private callDeviceMembership: CallDeviceMembership,
+        private _deviceIndex: number,
+        private _eventTimestamp: number,
         private readonly options: Options,
         private readonly logItem: ILogItem,
     ) {}
@@ -79,6 +81,14 @@ export class Member {
         return this.peerCall?.dataChannel;
     }
 
+    get deviceIndex(): number {
+        return this._deviceIndex;
+    }
+
+    get eventTimestamp(): number {
+        return this._eventTimestamp;
+    }
+
     /** @internal */
     connect(localMedia: LocalMedia) {
         this.logItem.wrap("connect", () => {
@@ -114,8 +124,10 @@ export class Member {
     }
 
     /** @internal */
-    updateCallInfo(callDeviceMembership: CallDeviceMembership) {
+    updateCallInfo(callDeviceMembership: CallDeviceMembership, deviceIndex: number, eventTimestamp: number) {
         this.callDeviceMembership = callDeviceMembership;
+        this._deviceIndex = deviceIndex;
+        this._eventTimestamp = eventTimestamp;
     }
 
     /** @internal */