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sipdtmf

What is the purpose of using DTMF in sip based softphone?

DTMF is used in some sip based softphone to handle payload type. But the process and the importance of using DTMF is not clear to me. Open source softphone like Red5phone and Sipdroid uses DTMF. Would anyone please explain the issue or point me somewhere I can find good enough explanation.

Thanks.

Solution

  • If you are calling to some machine-answered phone, it may asks you to choose from multiple menu items, then you will press a number for your choice. This number should be transmitted using DTMF to peer.

    This is what DTMF matters.

    I hope I didn't misunderstand your question.

    For the RTP payload of DTMF, please reference RFC2833.