How to choose dtmf mode

DTMF (dual tone multi frequency) is the signal to the phone company that you generate when you press an ordinary telephone's touch keys.

Without correct DTMF, a IVR could not understand what's customer input.

Usually we just need to make sure it's using correct dtmfmode in the trunk. The option is

dtmfmode= the options are

• auto
• inband
• info
• rfc2833

For example

dtmfmode=rfc2833

• For inbound/outbound, you need to make sure you configured correct dtmfmode same as your provider asked, in most case, use rfc2833
• When you are using inband, the codec need to be ulaw or alaw