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Which DTMF method - CUCM8.6 SIP trunk to Cisco 2900 VGWs?


I'm digging into interesting area, what are the best practices to configure DTMF relay between CUCM 8.6 Cluster and several Cisco ISRg2 voice gateways equipped with BRI/PRI HWICs for PSTN access.

I know this depends on many specific attributes which are what endpoints are used, what is the signaling protocol between CUCM and end points, etc. Some scenarios requires rfc2833 rtp-nte DTMF, some scenarios requires SIP KPML which is great for SIP phone supporting it. But none of method is universal cure for most of situations.

I've got many 6900 (sccp), 7900 (sccp) and 9951 (sip) endpoints deployed. Some of them use rfc2833, some of them use sip-kpml.

Currently I've got this configuration on dial-peer to CUCM  "dtmf-relay sip-kpml sip-notify", I'm considering adding rtp-nte as a last 3rd option. But I hope this will not be necessary.

On CUCM side I've enabled "Accept unsolicited notification" on SIP Trunk Security Profile to cisco voice GW's so it accepts "sip-notify". On SIP trunk there is "No preference" option as DTMF method.

I'm afraid if I enable "OOB and rfc2833" on SIP Trunk CUCM will use both methods for every single digit pressed which can lead into more intensive MTP utilization (which is said in SRND8.x).

Whats your opinion? How would you solve simillar scenarios?



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New Member

Which DTMF method - CUCM8.6 SIP trunk to Cisco 2900 VGWs?

I've overcome most of the issues with configuring DTMF between CUCM and Voice GW's/CUBE's like "sip-kpml sip-notify", and DTMF to ITSP provider like "rtp-nte". Seems it's working and if provider supports RFC2833 its a best way how to do it.

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