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Community Member

DTMF is not working in 50% of Outbound IVR based Calls (IPCC)


I am facing a problem in outbound ivr based calls that DTMF is not working in few of calls and working in few of calls as well. You can say 50/50.

We are using SIP as signaling between CUCM -> Gateways and CUCM -> CVP. Sip trunks has MTP checked and codec us 711uLaw.

A dialpeer is also configured on both outbound gateways which is mentioned below. It seems to be a resources problem. Dun know exactly where may be on gateways, cucm or cvp.


ICM 7.5.9

CUCM 7.0.2

Gateways 12.4(20)T4

Please advise if anybody can help and face same type of problem.



Voip Dial Peer

dial-peer voice 999 voip
description "Outbound voip for DTMF dialer with cvp"
incoming called-number .T
dtmf-relay rtp-nte h245-signal h245-alphanumeric
codec g711ulaw
fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback none
no vad

Pots Dial Peer through which calls are getting out to customers:

dial-peer voice 3330 pots
trunkgroup Outbound
tone ringback alert-no-PI
description "##### OB DIaling for Ufone Preference 1 #####"
destination-pattern 3.........
progress_ind connect enable 8
forward-digits all

Community Member

Re: DTMF is not working in 50% of Outbound IVR based Calls (IPCC

Hi Hammad,

First question is do you need MTP enabled on the SIP trunk?  Your gateway and CVP versions are high enough to where you do not need to set MTP Required on the trunk.  If you are worried about a dtmf replay mismatch, CUCM will automatically insert an MTP if it detects a dtmf delay mismatch.  There is no need to explicitly set one.  CVP and CUCM support rfc2833 and the dial-peer is set to rfc2833 as well (rtp-nte).  You shouldn't need an MTP in this call flow.

Try disabling the MTP requirement on the trunk and see if that makes a difference.  If not, can you get a sniffer capture from the gateway?  We can see if the gateway is passing DTMF on the bad calls.

If MTP is required for some reason, can you let me know if you are using software or hardware MTP resources?  Do you have any transcoders configured?  Send me a 'sh run' from each hardware MTP and transcoder configured.


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