Issue: Lag in start of Recording for Incoming Calls handled by Azure Communication service causing the first few seconds of the call to be missed out. This issue doenst happen when there is a lag when ACS answers the call. summary

Question

Issue: Lag in start of Recording for Incoming Calls handled by Azure Communication service causing the first few seconds of the call to be missed out. This issue doenst happen when there is a lag when ACS answers the call. summary

Mohammed Suhail 40

Note: its during the live call. Not on missed calls.

Praneeth Maddali 7,815 Reputation points Microsoft External Staff Moderator

2026-04-07T14:40:48.5266667+00:00

Hi @Mohammed Suhail

Thank you for contacting us about the Lag in start of Recording for Incoming Calls handled by Azure Communication service causing the first few seconds of the call to be missed out issue. We have begun looking into it and will share our suggestions with you as soon as possible. If you have any additional details or concerns in the meantime, please let us know. We appreciate your patience while we work on this.
Mohammed Suhail 40 Reputation points

2026-04-07T15:05:07.1366667+00:00

Hi @Praneeth Maddali if you open up a private message will share an call recordings for your refference.
Praneeth Maddali 7,815 Reputation points Microsoft External Staff Moderator

2026-04-07T15:12:01.86+00:00
Hi @Mohammed Suhail

Thank you for providing the detailed description of the issue. I understand that you're seeing the first few seconds of audio missing in recordings for incoming calls handled by Azure Communication Services, specifically when recording starts immediately on live calls (but not on missed calls or when there's a delay during answer).

This is a known timing behavior with ACS Call Recording. When StartRecording is invoked too early (right after AnswerCall), the recording backend needs a short time to initialize the media pipeline, so initial audio can be dropped.

The suggestion you shared is on the right track, but we can make it more precise for reliable results.

Recommended Solution:

Trigger StartRecording only after receiving the CallConnected event. This event confirms the call is fully established and media is flowing in both directions, which significantly reduces or eliminates the missing initial seconds.

Quick code pattern (C# example):

In IncomingCall handler > only AnswerCallAsync

In CallConnected handler > call StartRecordingAsync using the serverCallId

This is the standard pattern shown in Microsoft samples and quickstarts.

reference :

https://learn.microsoft.com/en-us/azure/communication-services/quickstarts/voice-video-calling/get-started-call-recording?pivots=programming-language-javascript

https://learn.microsoft.com/en-us/azure/communication-services/concepts/call-automation/call-automation

https://learn.microsoft.com/en-us/azure/communication-services/concepts/voice-video-calling/call-recording

Kindly let us know if the above helps or you need further assistance on this issue.

Please "upvote" if the information helped you. This will help us and others in the community as well
Praneeth Maddali 7,815 Reputation points Microsoft External Staff Moderator

2026-04-08T12:36:16.57+00:00

Hi @Mohammed Suhail

Just following up to see if your issue has been resolved or if you had a chance to review my earlier comment?