Outbound DTMF not working from H323

[iptsupport]

Hello ,

We recently configure a SIP trunk to external call center  which is connected to our CUCM.
we have cisco router that work in protocol H323   that  routes all calls to our Call Manager.
outbound DTMF to SIP trunk is not working.
in sip trunk we configure RFC2833 and
in cisco router we configure
dial-peer voice 6690 voip
preference 1
destination-pattern 6690
session target ipv4:1.1.1.1
voice-class codec 1
voice-class h323 1
dtmf-relay h245-alphanumeric
no vad

[Roger Kallberg]

Recommend you to change the trunk between the voice gateway and CM to SIP and try again.

[Nithin Eluvathingal]

Since you are using sip trunk from isp it’s recommended to move to sip trunk between cucm and gateway and get rid of h323 protocol.

if you invoke MTP this will work.

Have you checked with isp what dtmf they support ? Is it in and or outband ?

[Jonathan Schulenberg]

H.323 is so old (and neglected) that I’m not sure CUCM ever supported DTMF interop between it and SIP. Your only chance of getting it to work would be invoking an IOS software MTP (not CUCM IPVMSA) to interwork from H.323 alphanumeric to RFC2833. An MTP is as likely to create problems as it is to fix them though; it also limits your capacity.

As others have suggested: migrate the other gateway to SIP.

PS- H.323 is fully deprecated starting in IOS-XE 17.6.

https://www.cisco.com/c/en/us/products/collateral/unified-communications/unified-border-element/bulletin-c25-2479306.html