UACSTA, short for User Agent Computer Supported Telecommunications Application, standardizes a very powerful and flexible set of application services to observe and control voice and non-voice media calls as well as control and observe non-call related features. It is not supported on all models or phone providers.
Below is the original question from customer:
This is possible and supported by some VoIP phone providers, but we have been unable to find uaCSTA in the Yealink phones. May I know if yealink support uaCSTA?
Yealink phone running on V81 supports the uaCSTA feature, you can upgrade the phone and test the feature in your side. For more information, please refer to Yealink administrator guide in page 525: