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Cisco Bug: CSCum17510 - CUCM SRND 9.x document MGCP DTMF portion needs more explanation.

Last Modified

Jun 03, 2014

Products (1)

  • Cisco Collaboration Systems Release

Known Affected Releases

9.1(1)

Description (partial)

Symptom:
MGCP gateway DTMF related part require more explanation .

Curently I can see below sentence for enabling DTMF relay RFC 2833 on MGCP gateway. Which is wrong.

"Use the fm-package command to enable DTMF via RFC 2833, available as of Cisco IOS Release 12.4(6)T."

Please change update it as below (I have already double checked it with DE and tested in LAB.):

Please use command "mgcp dtmf-relay voip codec all mode nte-ca" for enabling DTMF RFC 2833 (RTP-NTE) on mgcp gateway.

Currently we can not force MGCP gateway to advertise only RFC 2833. On enabling In band gateway will alwways advertise both inband and OOB dtmf.
It is CUCM who decides what should be selected. And CUCM will inform the gateway it over MDCX message.

If both the endpoints are mgcp registered to CUCM , there is no way we can invoke  RFC 2833 for DTMF relay. Because after enabling inband dtmf
both the gateways will advertise inband and oob dtmf methods. As per design CUCM will select OOB if it get a choice across inband and out of band.

On other end points like SIP trunk we have options to select DTMF method on CUCM admin page. Curently MGCP does not have this option.

http://www.cisco.com/en/US/partner/docs/voice_ip_comm/cucm/srnd/8x/gateways.html#wp1044091

Page number 199 .

Conditions:
Currently we can not force MGCP gateway to advertise only RFC 2833. On enabling In band gateway will alwways advertise both inband and OOB dtmf.
It is CUCM who decides what should be selected. And CUCM will inform the gateway it over MDCX message.

If both the endpoints are mgcp registered to CUCM , there is no way we can invoke  RFC 2833 for DTMF relay. Because after enabling inband dtmf
both the gateways will advertise inband and oob dtmf methods. As per design CUCM will select OOB if it get a choice across inband and out of band.

On other end points like SIP trunk we have options to select DTMF method on CUCM admin page. Curently MGCP does not have this option.
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