Media Termination Point

MTP

A media termination point (MTP) is an entity that accepts two full-duplex media streams. It bridges the streams together and allows them to be set up and torn down independently. The streaming data received

from the input stream on one connection is passed to the output stream on the other connection, and vice versa.

MTPs have many possible uses, such as:

• Re-Packetization of a Stream

• DTMF Conversion

• Protocol-specific usage

 – DTMF Relay over SIP Trunks

 – H.323 Supplementary Services

 – H.323 Outbound Fast Connect

Re-Packetization of a Stream : An MTP can be used to transcode G.711 a-law audio packets to G.711 mu-law packets and vice versa, or it can be used to bridge two connections that utilize different packetization periods

DTMF Conversion: DTMF tones are used during a call to signal to a far-end device for purposes of navigating a menu system, entering data, or other manipulation. There are several methods for sending DTMF over IP, and two communicating endpoints might not support a common procedure. In these cases, Unified CM may dynamically insert an MTP in the media path to convert DTMF signals from one endpoint to the other.

DTMF Relay between Endpoints in the Same Unified CM Cluster

Calls between two non-SIP endpoints do not require MTPs.

Calls between two Cisco SIP endpoints do not require MTPs.

A combination of a SIP endpoint and a non-SIP endpoint might require MTPs.

DTMF Relay over SIP Trunks

Media Termination Point Required: Checking this option on the SIP trunk assigns an MTP for every outbound call. This statically assigned MTP supports only the G.711 codec or the G.729 codec, thus limiting media to voice calls only.

Early Offer support for voice and video calls (insert MTP if needed): Checking this option on the SIP Profile associated with the SIP Trunk inserts an MTP only if the calling device cannot provide Unified CM with the media characteristics required to create the Early Offer (for example, where an inbound call to Unified CM is received on a Delayed Offer SIP trunk or a Slow Start H.323 trunk). This option is available only with Unified CM 8.5 and later releases.

Reference: CUCM 9.0 SNRD 
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