DTMF ON ISDN and CUCM MGCP

[kennedymacharia]

Hi all,

I have a configured MGCP and the gateway is reqistered with an E1 line. The problem is that DTMF is not working. my MGCP config is as follows

mgcp
mgcp call-agent 172.18.30.10 2427 service-type mgcp version 0.1
mgcp dtmf-relay voip codec low-bit-rate mode nse
mgcp rtp unreachable timeout 1000 action notify
mgcp modem passthrough voip mode nse
mgcp package-capability rtp-package
mgcp package-capability sst-package
mgcp package-capability pre-package
mgcp package-capability fm-package
no mgcp package-capability res-package
no mgcp timer receive-rtcp
mgcp sdp simple
mgcp fax t38 inhibit
mgcp behavior rsip-range tgcp-only
mgcp behavior comedia-role none
mgcp behavior comedia-check-media-src disable
mgcp behavior comedia-sdp-force disable
mgcp profile default
ccm-manager mgcp

[Ayodeji Okanlawon]

Try this..

conf t

mgcp dtmf-relay voip codec all mode out-of-band

no mgcp

mgcp

[Mohammed al Baqari]

+5 Deji.

To explain the commands, mgcp dtmf-relay voip codec low-bit-rate mode nse will enable DTMF as NSE for low bit rate codecs such as g729, ilbc, gsm. G711 will use inband voice, i.e. dtmf relay won't work for g711.

The command applied by Deji will use out-of-band DTMF for all codecs including 711. This is the recommended way for MGCP.

A note on NSE, it uses fixed payload type of 100 and won't be negotiated. This means that for SCCP phones it won't work as it doesn't negotiate with CUCM and no MTP will be inserted. This is different from RTP-NTE (CA controlled or GW controlled) which negotiates payload type. Therefore, try to avoid NSE

[spazziani]

Hi,

did you solve the problem ? I have a similar problem. I have Gateway ISDN with MGCP, and I have the follow configuration in the environment:

mgcp dtmf-relay voip codec all mode out-of-band
mgcp package-capability fm-package

The configuration on the CUCM in MGCP field TYPE OF DTMF RELAY "default is Current GW Config"

I have phone is using SCCP and SIP Protocol to registering with the CUCM.

The phone are registered with the protocol SCCP, when they call to PSTN the DTMF working fine.

The phone are registered with protocol SIP, when they call to PSTN the DTMF isn't work.

I saw in some documentation there is a command mgcp package-capability dtmf-package, so I don't have this command in my configuration, is this command could cause the problem?

[Ratheesh Kumar]

Hi there

Could you check this below bug and the workaround and see that helps..

GW sends dtmf in band while it is configured to support only out of band

CSCsc19202

Description

Symptoms : DTMF digits may not get recognized by your IVR system. If you
listen carefully for the
DTMF tone that is sent by gw, you may hear doubl sound.
Condition : GW is a MGCP gw which has configured with mgcp dtmf-relay voip
codec all mode out-of-
band or no mgcp dtmf voip, and codec g711u is used.
Workaround : Use codec g729 to make the in band dtmf unrecognizable.

Hope this Helps

Cheers

Rath!

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[Ayodeji Okanlawon]

Hi,

This is normal. Your MGCP is doing DTMF out-of-band. Your sip phones are doing rtp-nte and your sccp phones are doing out-of-band. So DTMF will work on SCCP phones but your sip phones will require MTP for DTMF to work.

You can configure your MGCP gateway to use rtp-nte with the command below but you may now have issues with your SCCP phones.

mgcp dtmf-relay voip codec all mode nte-gw

NB if you make this change on your mgcp gateway, you need to reset the mgcp process as shown below:

conf t

no mgcp

mgcp

Again if you dont want to use rtp-nte on your mgcp gateway, then you need to have MTP for this to work

[spazziani]

Hi Ayodeji,

Who should submit the MTP? Does the MRGL configuration of the phone or the MRGL configuration of GW MGCP?

I have configured MRGL only on the phones in GW MGCP I have not configured the MRGL.

Thanks,

[Ayodeji Okanlawon]

Apply MRGL with an MTP to the gateway. Once you are done, reset the mgcp process as mentioned earlier.

[spazziani]

Hi,

When I enable MRGL in the GW MGCP configuration will all media pass through MTP not only the DTMF requests?

If the media is going through MTP, do I have to have enough media resources right?

Thanks,

[Ayodeji Okanlawon]

Yes that is correct, so you should configure a software IOS MTP.