diff --git a/lib/src/voip/call.dart b/lib/src/voip/call.dart
index 7f887be3..2b22f5aa 100644
--- a/lib/src/voip/call.dart
+++ b/lib/src/voip/call.dart
@@ -30,11 +30,19 @@ import 'package:matrix/src/utils/cached_stream_controller.dart';
 /// version 1
 const String voipProtoVersion = '1';
 
-/// The default life time for call events, in millisecond.
-const lifetimeMs = 10 * 1000;
+class Timeouts {
+  /// The default life time for call events, in millisecond.
+  static const lifetimeMs = 10 * 1000;
 
-/// The length of time a call can be ringing for.
-const callTimeoutSec = 60;
+  /// The length of time a call can be ringing for.
+  static const callTimeoutSec = 60;
+
+  /// The delay for ice gathering.
+  static const iceGatheringDelayMs = 200;
+
+  /// Delay before createOffer.
+  static const delayBeforeOfferMs = 100;
+}
 
 /// Wrapped MediaStream, used to adapt Widget to display
 class WrappedMediaStream {
@@ -551,7 +559,7 @@ class CallSession {
 
     /// Send select_answer event.
     await sendSelectCallAnswer(
-        opts.room, callId, lifetimeMs, localPartyId, remotePartyId!);
+        opts.room, callId, Timeouts.lifetimeMs, localPartyId, remotePartyId!);
   }
 
   Future<void> onNegotiateReceived(
@@ -581,7 +589,7 @@ class CallSession {
       if (description.type == 'offer') {
         final answer = await pc!.createAnswer({});
         await sendCallNegotiate(
-            room, callId, lifetimeMs, localPartyId, answer.sdp!,
+            room, callId, Timeouts.lifetimeMs, localPartyId, answer.sdp!,
             type: answer.type!);
         await pc!.setLocalDescription(answer);
       }
@@ -939,13 +947,18 @@ class CallSession {
             video_muted: localUserMediaStream!.stream!.getVideoTracks().isEmpty)
       });
 
+      await pc!.setLocalDescription(answer);
+      setCallState(CallState.kConnecting);
+
+      // Allow a short time for initial candidates to be gathered
+      await Future.delayed(Duration(milliseconds: 200));
+
       final res = await sendAnswerCall(room, callId, answer.sdp!, localPartyId,
           type: answer.type!,
           capabilities: callCapabilities,
           metadata: metadata);
       Logs().v('[VOIP] answer res => $res');
-      await pc!.setLocalDescription(answer);
-      setCallState(CallState.kConnecting);
+
       inviteOrAnswerSent = true;
       _answeredByUs = true;
     }
@@ -964,7 +977,8 @@ class CallSession {
     }
     Logs().d('[VOIP] Rejecting call: $callId');
     await terminate(CallParty.kLocal, CallErrorCode.UserHangup, shouldEmit);
-    await sendCallReject(room, callId, lifetimeMs, localPartyId, reason);
+    await sendCallReject(
+        room, callId, Timeouts.lifetimeMs, localPartyId, reason);
   }
 
   Future<void> hangup([String? reason, bool suppressEvent = false]) async {
@@ -1055,6 +1069,13 @@ class CallSession {
       return;
     }
 
+    if (pc!.iceGatheringState ==
+        RTCIceGatheringState.RTCIceGatheringStateGathering) {
+      // Allow a short time for initial candidates to be gathered
+      await Future.delayed(
+          Duration(milliseconds: Timeouts.iceGatheringDelayMs));
+    }
+
     if (callHasEnded) return;
 
     final callCapabilities = CallCapabilities()
@@ -1063,12 +1084,12 @@ class CallSession {
     final metadata = _getLocalSDPStreamMetadata();
     if (state == CallState.kCreateOffer) {
       await sendInviteToCall(
-          room, callId, lifetimeMs, localPartyId, null, offer.sdp!,
+          room, callId, Timeouts.lifetimeMs, localPartyId, null, offer.sdp!,
           capabilities: callCapabilities, metadata: metadata);
       inviteOrAnswerSent = true;
       setCallState(CallState.kInviteSent);
 
-      inviteTimer = Timer(Duration(seconds: callTimeoutSec), () {
+      inviteTimer = Timer(Duration(seconds: Timeouts.callTimeoutSec), () {
         if (state == CallState.kInviteSent) {
           hangup(CallErrorCode.InviteTimeout, false);
         }
@@ -1077,7 +1098,7 @@ class CallSession {
       });
     } else {
       await sendCallNegotiate(
-          room, callId, lifetimeMs, localPartyId, offer.sdp!,
+          room, callId, Timeouts.lifetimeMs, localPartyId, offer.sdp!,
           type: offer.type!,
           capabilities: callCapabilities,
           metadata: metadata);
@@ -1088,6 +1109,11 @@ class CallSession {
     Logs().i('Negotiation is needed!');
     makingOffer = true;
     try {
+      // The first addTrack(audio track) on iOS will trigger
+      // onNegotiationNeeded, which causes creatOffer to only include
+      // audio m-line, add delay and wait for video track to be added,
+      // then createOffer can get audio/video m-line correctly.
+      await Future.delayed(Duration(milliseconds: Timeouts.delayBeforeOfferMs));
       final offer = await pc!.createOffer({});
       await _gotLocalOffer(offer);
     } catch (e) {