Media Termination Point Required Problem

[MehmetKaya]

Device > Gateway > H323 > Checking Media Termination Point Required and Enable Inbound FastStart

I’m not a fan of forcing every call to “Use MTP Required” on Device  > Gateway > H323 and Inbound Fast Start (which also forces MTP)

Anyone disagree with me that best practice says you don’t use G729 as  default codec and have CallManager doing Software MTP transcoding from  G729 to G711 and vice

If you want transcoding you really should do it in hardware, eh?

I’m trying to figure out if someone knew what they were doing and  wanted to force software transcoding at this customer…or didn’t really  know what they were doing.

When I select(media Termination Point on H.323 GW) the can not clict the transfer button. When dont select the (media Termination Point on H.323 GW) I can clict to transfer and can transfer but after transfer the called client can not hear anything. And later the call closed.

how can solve this problem. Have we need to use hardware mtp ? We want to solve this problem with software mtp(on mcs servers). When we use g.711 codec there is not any problem. but when try with G.729 codec the problem which ı meantioned occured.

[Vinay Kumar Dharmaraj]

Hi,

Callmanager software MTP do not support G729 codec. It supports only G711alaw and G711ulaw codec. You should use hardware transcoder to support G729 to G711 transcoding.

Refer the SRND for more information,

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/7x/media.html#wp1058085

Hope this answers your question.

Regards,

Vinay

[Payal Bhaduri]

Hi Mehmet,

The hardware MTP uses a DSP resource for endpoints using the same G.711 codec but a different packetization time.

You need a transcoder to do g729 to g711.

[MehmetKaya]

He Payal,

As you said we need to use hardware mtp using the same g.711 codec but different packetization time.(ok)

If so we use ıos software mtp for what?. As configured  below;

The following example configuration is for a Cisco IOS software-based MTP:

!

sccp local Vlan5

sccp ccm 10.10.5.1 identifier 5 version 5.0.1

! Communications Manager IP address (10.10.5.1)

sccp

!

sccp ccm group 5

bind interface Vlan5

associate ccm 5 priority 1

associate profile 5 register MTP000E83783C50

! MTP name (MTP000E83783C50) ... must match the Unified CM MTP name.

!

dspfarm profile 5 mtp

description software MTP

codec g711ulaw

codec pass-through

maximum sessions software 500

associate application SCCP

[MehmetKaya]

Hi Payal,

I think software mtp just use one codec and different packetization time?

Software MTP (Based on Cisco IOS)

•The  capability to provide a software-based MTP on the router is available  beginning with Cisco IOS Release  12.3(11)T for the Cisco 3800 Series  Routers and Release 12.3(8)T4 for other router models.

•This  MTP allows configuration of any of the following codecs, but only one  may be configured at a given time: G.711 mu-law and a-law, G.729a,  G.729, G.729ab, G.729b, and passthrough. Some of these are not pertinent  to a Unified CM implementation.

•The  router configuration permits up to 500 individual streams, which  support 250 transcoded sessions. This number of G.711 streams generates  5 Mbytes of traffic.

[Payal Bhaduri · Accepted solution]

Hi Mehmet,

The link below will give you further details:

http://www.cisco.com/en/US/docs/ios/12_3/vvf_c/interop/intcnf2.html

MTP

A Media Termination Point (MTP) bridges the media streams between two connections allowing Cisco Unified Communications Manager to relay calls that are routed through SIP or H.323 endpoints.

The following MTP resources are supported for Cisco Unified Communications Manager 4.0 (formerly known as Cisco CallManager 4.0) and later releases:

•Software MTP—Software-only implementation that does not use a DSP resource for endpoints using the same codec and the same packetization time.

•Hardware MTP—Hardware-only implementation that uses a DSP resource for endpoints using the same G.711 codec but a different packetization time. The repacketization requires a DSP resource so it cannot be done by software only. Cisco Unified Communications Manager also uses the term software MTP when referring to a hardware MTP.

•Transcoder as MTP—Implementation that uses a DSP resource for endpoints using the same G.711 codec (on both legs) or a mixture of different supported codecs. This functionality is used by Cisco Unified Communications Manager to view the transcoders as usable MTP resources (if they are available in the pool) and enables Cisco Unified Communications Manager to use MTP resources more effectively when a call is deemed to use a transcoder and an MTP resource at the same time.