[asterisk-users] How to Busy signals on DAHDI

giovanni.v iax at keybits.org
Thu Feb 6 04:09:52 CST 2014

Il 05/02/2014 8.42, Olivier ha scritto:
>     channel then it depends upon what you have the priindication option
>     set to.  With
>     priindication=outofband then a busy cause code is sent to the
>     network and the call
>     is hung up.  With priindication=inband then a busy tone is sent
>     after a possible
>     PROGRESS message.

> I'm gonna check what's really happening from caller's perspective when
> such parameter is set.
> I would expect a busy tone (and the opportunity for automatic redialing).

Sending a busy signalling on D channel (priindication=outofband) will go 
back into the telephone network exactly the same way the called party 
was really busy... so no charge, busy tone, not completed call on the 
caller side.

Just a couple of notes about priindication=inband.
- Usually sending in-band audio on a "not connected" state is not 
allowed unless a special setup is done by the isdn provider.
- While sending in-band audio or busy signalling on D channel will make 
no difference (from the caller perspective) if the call is originated 
from an analog pstn line anything else (gsm->isdn, sip->isdn...) will 
fail to get a proper state for that call.
Definitely I will never use it unless it is required, like the mandatory 
price information message to be sent **before** connection if you run a 
"value added" incoming service billed to the caller.

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