Hi,
There are several methods of transporting DTMF over SIP trunks, these methods can be classified as out-of-band (OOB) and in-band signaling. In-band DTMF transport methods send either raw or signaled DTMF tones within the RTP stream
Out-of-band signaling methods transport DTMF tones outside of the RTP path, either directly to and from the endpoints or through a call agent such as Cisco Unified CM, which interprets and/or forwards these tones as required.
In Cisco CUCM SIP trunks there are three options
1. RFC 2833
2. RFC 2833 and OOB
3. No preference
RFC2833 Carries dtmf using signalled DTMF tones in the RTP payload.
Over Unified CM SIP trunks, Cisco recommends configuring the DTMF Signaling Method to
No Preference. This setting allows Unified CM to make an optimal decision for DTMF and to minimize MTP allocation
In CUBE, dtmf methods are defined either globally on in dial-peers. Typically RFC2833 is used which usually is defined by dtmf-relay rtp-nte. You can also define multiple dtmf method on a sip dial-peer to simulate the no preference option on cico CUCM sip trunks. This aims to achive the same purpose as the No preference option which is to minimize/eliminate the need for MTP.
Out-of-band (OOB) SIP DTMF signaling methods include Unsolicited Notify (UN), Information (INFO), and Key Press Markup Language (KPML).
On the CUCM sip trunk you can define RF2833 and OOB as yout dtmf method, this will be equivalent to configuring this on a CUBE with a sip dial-peer
dial-peer voice 203 voip
session protocol sipv2
dtmf-relay rtp-nte digit-drop sip-kpml
You can read more from the SRND
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/8x/trunks.html#wp1126482
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