Refer to the exhibit. The SDP offer/answer has been completed successfully but there is no DTMF when users press keys. What is the cause of the issue?

Question

Exhibit

Options

• APayload type 110 was negotiated rather than type 101.
• BDTMF was negotiated properly in these messages.
• CG.729 rather than G.711ulaw was negotiated.
• DDTMF was not negotiated on the call.

• A
  3% (1)
• B
  12% (4)
• C
  9% (3)
• D
  76% (25)

Explanation

It is offered 18 (g729) and 110 (type-event), however the answer only contains 18. Therefore, DTMF was not negotiated.

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