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New Member

force mgcp gateway to use only G711 codec

Hi all,

Is there any way to configure a cisco mgcp gateway to only support G711 codec, i have see a command on the gateway "mgcp codec" that could do this.

Can any one help me on this

Many thanks


Re: force mgcp gateway to use only G711 codec

There is no specific requirement to configure MGCP for G711 through the command 'mgcp codec'.

The reason for this is that the mgcp codec is automatically configured for G711ulaw as soon as MGCP is enabled on the gateway.

I have capture the output of a show mgcp after enabling in on the gateway for your reference:-


Router(config)#do show mgcp

MGCP Admin State ACTIVE, Oper State ACTIVE - Cause Code NONE

MGCP call-agent: none Initial protocol service is MGCP 0.1

MGCP validate call-agent source-ipaddr DISABLED

MGCP validate domain name DISABLED

MGCP block-newcalls DISABLED

MGCP send SGCP RSIP: forced/restart/graceful/disconnected DISABLED

MGCP quarantine mode discard/step

MGCP quarantine of persistent events is ENABLED

MGCP dtmf-relay for VoIP is SDP controlled

MGCP dtmf-relay for voAAL2 is SDP controlled

MGCP voip modem passthrough disabled

MGCP voaal2 modem passthrough disabled

MGCP voip modem relay: Disabled

MGCP T.38 Named Signalling Event (NSE) response timer: 200

MGCP Network (IP/AAL2) Continuity Test timer: 200

MGCP 'RTP stream loss' timer: 5

MGCP request timeout 500

MGCP maximum exponential request timeout 4000

MGCP gateway port: 2427, MGCP maximum waiting delay 3000

MGCP restart delay 0, MGCP vad DISABLED


MGCP system resource check DISABLED

MGCP xpc-codec: DISABLED, MGCP persistent hookflash: DISABLED

MGCP persistent offhook: ENABLED, MGCP persistent onhook: DISABLED

MGCP piggyback msg ENABLED, MGCP endpoint offset DISABLED

MGCP simple-sdp DISABLED

MGCP undotted-notation DISABLED


MGCP codec type g711ulaw, MGCP packetization period 20


MGCP JB threshold lwm 30, MGCP JB threshold hwm 150

MGCP LAT threshold lwm 150, MGCP LAT threshold hwm 300

MGCP PL threshold lwm 1000, MGCP PL threshold hwm 10000

MGCP CL threshold lwm 1000, MGCP CL threshold hwm 10000

MGCP playout mode is adaptive 60, 40, 200 in msec

MGCP Fax Playout Buffer is 300 in msec

MGCP media (RTP) dscp: ef, MGCP signaling dscp: af31

MGCP default package: trunk-package

MGCP supported packages: gm-package dtmf-package trunk-package line-package

hs-package atm-package ms-package dt-package mo-package

res-package mt-package fxr-package md-package

MGCP Digit Map matching order: shortest match

SGCP Digit Map matching order: always left-to-right

MGCP VoAAL2 ignore-lco-codec DISABLED

MGCP T.38 Max Fax Rate is DEFAULT



MGCP T.38 Fax NSF Override is DISABLED

MGCP T.38 Fax Low Speed Redundancy: 0

MGCP T.38 Fax High Speed Redundancy: 0

MGCP Fax relay SG3-to-G3: ENABLED

MGCP control bind :DISABLED

MGCP media bind :DISABLED

MGCP Upspeed payload type for G711ulaw: 0, G711alaw: 8

MGCP Dynamic payload type for G.726-16K codec

MGCP Dynamic payload type for G.726-24K codec

MGCP Dynamic payload type for G.Clear codec

MGCP Dynamic payload type for NSE is 100

MGCP Dynamic payload type for NTE is 99

MGCP rsip-range is enabled for TGCP only.

MGCP Guaranteed scheduler time is disabled

MGCP DNS stale threshold is 30 seconds



New Member

Re: force mgcp gateway to use only G711 codec

Hi Allan,

Is there any configuration to disable the support for G729 codec on the gateway and only support G711.


Re: force mgcp gateway to use only G711 codec

Hi Patricio, are there specific reasons why you are trying to limit or influence which codec is selected for inbound and/or outbound calls?

Your Regions and Device-Pools will determine what codec your endpoints will negotiate, therefore G729 will only be used if you explicitly configure it.



New Member

Re: force mgcp gateway to use only G711 codec

Hi Allan,

I have a specific scenario where on the headquartes i have a cisco mgcp gateway with a voice guide that has to be played in G711 codec to the brach office, but since the branch has slow link i want to add a trancoding resorce betwen the heardquatres and the branch to force a G711 betwen the headquarter and the trancoder and a G729 betwen the branch and the transcoder. The gateway on the headquarters need to be configured with mgcp.

Many thanks