Which media resource supports DTMF interworking?

• A. SIP Normalization Proxy
• B. Media Gateway
• C. MTP
• D. DTMF Relay

Answer: (C)

DTMF interworking happens when two network paths use different ways of carrying DTMF tones, so the media path itself must translate and relay those digits correctly between sides. The Media Termination Point (MTP) is designed for advanced media processing in Cisco deployments, including interworking DTMF across different transport methods (for example, converting between RFC2833 DTMF in RTP and in-band tones or other DTMF representations). By sitting in the media path, the MTP ensures digits pressed by users are understood on the other end, regardless of which DTMF method each side uses.

SIP Normalization Proxy handles signaling normalization, not the actual media DTMF translation. A Media Gateway bridges media between networks and may carry DTMF, but interworking specifically hinges on the media-processing capability of an MTP. DTMF Relay focuses on relaying DTMF signaling, not performing the full media interworking function. So the MTP is the correct choice for DTMF interworking.