No ringing sound during PSTN call

Ilya Siamenchanka 0

Hi, we use azure communication services to make calls to our clients phone numbers. We used to have a ringing sound before client pick up the phone. Now there is no sound, but as soon they pick up the phone, it works fine. So it's not a general sound issue, just ringing sound is missing.

All packages are up-to-date, and we have also reproduced the issue on sample-hero with our connection string and phone number.

However, it works fine on azure portal on "Try phone calling" page.

Thank you

Bhargavi Naragani 1,375 Reputation points Microsoft External Staff

2025-03-03T23:27:46.44+00:00

Hi @Ilya Siamenchanka,

It seems that the problem is actually with the ringtone when making PSTN calls using Azure Communication Services (ACS), the call goes through perfectly, but there is no ringtone before the recipient answers. As the feature is working properly when using the "Try phone calling" page on the Azure portal.

Ensure the app has permissions for audio playback and verify that the audio output is set correctly (speakers or headphones).

During the call setup, the ringbackToneEnabled setting (or equivalent) needs to be configured correctly. Incorrect or missing parameters may occasionally result in this situation.

Sometimes, the audio output routing could be the cause of the ringtone not playing on the target device. Double-check that the default audio device is configured correctly.

Since you stated you re-created this on the sample-hero app, ensure that the connection string and phone number are passed appropriately. You can also double-check your code with the official sample and check for any differences.

Despite the fact that you stated that the packages are updated, we would suggest double-checking the ACS Calling SDK version and related dependencies to eliminate any version issues.

Turn on SDK logging to capture details and identify any audio errors during the call initiation phase.

Run the application on different devices or browsers to determine if the issue is device specific.

Also refer to the below documentations:
https://learn.microsoft.com/en-us/azure/communication-services/concepts/best-practices?tabs=windows&pivots=platform-web
https://learn.microsoft.com/en-us/azure/communication-services/how-tos/calling-sdk/push-notifications?pivots=platform-web
Hope the above provided information help in better understanding and help you resolve the issue, if you have any further concerns or queries, please feel free to reach out to us.
If the answer is helpful, kindly Upvote it.
Ilya Siamenchanka 0 Reputation points

2025-03-04T08:29:28.0566667+00:00

Hi and thank you for the reply.

As sound works fine after client picks up the call, I assume there are no issues with permissions or audio output.

As I said before we can easily reproduce it on sample-hero and the call by itself is working, so I don't expect issues with connection string or phone number.

You've mentioned ringbackToneEnabled setting, where can I set it? I cannot find it(or anything similar) in the documentation, can you please provide more details?

Thanks in advance
Bhargavi Naragani 1,375 Reputation points Microsoft External Staff

2025-03-04T16:54:54.7933333+00:00

Hi @Ilya Siamenchanka,

I apologize for the confusion regarding the ringbackToneEnabled setting. I made a mistake on that point. There isn't any setting by the name ringbackToneEnabled in the Azure Communication Services SDK. Ringing sound prior to call pickup is usually controlled on the ACS backend, and since it already works on the "Try phone calling" page of the Azure portal, there should be a problem somewhere on the client-side implementation.

Make sure the CallClient and CallAgent are configured correctly. Missing configurations in the call options at times may cause pre-call audio problems.

Double-check the usage of the startCall method. Make sure it's configured as per the official documentation: Place and Receive PSTN Calls

You can log call diagnostics to determine if there are errors or warnings that specifically show up related to the ringtone or signaling. Diagnostic Events

Just to eliminate environmental issues, have a go at running the sample-hero app on another device or network. This will isolate whether the problem may be caused by the local environment.

if you have any further concerns or queries, please feel free to reach out to us.
Bhargavi Naragani 1,375 Reputation points Microsoft External Staff

2025-03-05T16:52:36.7233333+00:00

Hi @Ilya Siamenchanka,
Sorry for any previous inconvenience.
Just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Ilya Siamenchanka 0 Reputation points

2025-03-06T12:48:08.4066667+00:00

Hi @Bhargavi Naragani
No, we still have an issue. We are pretty sure it worked before and call by itself is still working fine, so we are a bit stuck here. It will be great if you have any ideas of what we can try. And as I said before it's reproducible on the sample-hero project, so I don't think it can be a code issue.

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No ringing sound during PSTN call

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