Sending DTMF after calling a number on WP7

I am trying to handle the classic problem of sending DTMF notes after calling a certain n开发者_运维问答umber through PhoneCallTask in WP7.

Does anyone know the trick to do so? Does the SDK support RFC-2806?

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Your app does not have access to the phone call input/output audio and is also deactivated for the duration of the phone call in the platform's current state.