let say that you want to play 5 audio files in Asterisk one after one and give the user the option to use DTMF from the very beginning,
for doing it you have to join all those files to one big audio file,
have to do it ?
you can use the free software MediaJoin. i found it very easy to use and very simple ,
you can find it in http://www.tucows.com/preview/396569
in sip you have the option to hangup call by header,
the first question that arise is for what ?
ok ,imagine the next scenario : you use openser as proxy for enable calls from voip clients to pstn network and you want to limit the calls according to balance etc,
because the openser is stateless you can’t limit the call from openser side,
but you can send to the pstn provider another header: session-expires,
to use this header in the openser use : append_hf(”Session-Expires:$avp(s:res4);Refresher=uac\r\n”);
$avp(s:res4) hold the time in seconds,
how it’s work ?
this header is saying to the pstn side that you limit the session to x second’s and if you want to change it is in your responsibility and because you won’t send another invite to refresh this session the provider will have to send bye request,
please note : most of the pstn providers will not agree to session with less than 90 seconds
not all the providers are support this header