what DTMF relay method that a Cisco phone (Type A or Type B) uses by default?

[Oak Ridge]

can we change the method, like from oob to ib if the phone (type b) supports rfe 2833?

[Manish Gogna]

Hi Oak,

You can check the following doc for dtmf related queries

https://supportforums.cisco.com/blog/154706

HTH

Manish

[Oak Ridge]

thanks but your blog doesn't answer my question.

Take type B SCCP phone as an example.  Documents says it support RFC 2833. But what is the default behavior? For example, if we have a SCCP type B phone:

SCCP Type B Phone-----CUCM-----H225 Gatekeeper-----CUCM------SCCP type b PHone

what DTMF method will be used as default?

[Manish Gogna]

In Skinny phones, OOB (KeyPadButton Signal) and RFC2833 are enabled by default. However, RFC2833 can be disabled from device page.

When DTMF originates from CUCM, H245 Signal is used. From gateway side, the dtmf can originate as either  H245 Alphanumeric or Signal based on what is configured in the dial peers. Signal takes precedence however over alphanumeric.

CUCM supports only Out-of-Band DTMF mechanism for H323, however note that for gateways / CUBE, it is possible to use in-band RFC2833 mechanism too for DTMF. Take the eg. of CUBE < -- > CUBE scenario.

HTH

Manish