====== How to choose dtmf mode ======
===== What is DTMF =====
DTMF (dual tone multi frequency) is the signal to the phone company that you generate when you press an ordinary telephone's touch keys. 
===== What's DTMF for =====
Without correct DTMF, a IVR could not understand what's customer input.
===== Set DTMF =====
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
<code>
dtmfmode=rfc2833
</code>

{{:en:faq:dtmfmode.png?768|}}

<note tip>In the default template, astercc is using rfc2833</note>

===== How to config DTMF =====

  * 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