Sign in with Microsoft
Sign in or create an account.
Select a different account.
You have multiple accounts
Choose the account you want to sign in with.


Consider the following scenario:

  • You deploy a dual tone multi-frequency (DTMF) based Interactive Voice Response (IVR) application in a Microsoft Skype for Business Server 2015 environment.

  • The application is developed by using Unified Communications Managed API.

  • The application joins a conference.

  • A user connects to the application, and then the user starts pressing DTMF digits.

In this scenario, the DTMF tone is missing.


This issue occurs because the Audio Video Multipoint Conferencing Unit (AVMCU) does not process the DTMF tone when the DTMF packets that carry the end of tone flag are dropped in the network.


To fix this issue, install the following updates:

Need more help?

Want more options?

Explore subscription benefits, browse training courses, learn how to secure your device, and more.

Communities help you ask and answer questions, give feedback, and hear from experts with rich knowledge.

Was this information helpful?

What affected your experience?
By pressing submit, your feedback will be used to improve Microsoft products and services. Your IT admin will be able to collect this data. Privacy Statement.

Thank you for your feedback!