[Asterisk-Users] SIP extension "busy" when not available ??

[Rich Adamson]

> How come * says 1010 is BUSY in the trace below? I would have guessed
> "UNAVAILABLE" since 1010 is not logged on/registered.

That's what has been programmed in the asterisk code and has been that way
since the beginning of time. I don't like it either, but I'm not a programmer
and can't change it.

The logical response really should be Unavailable, but apparently there must
be a reason why no one has changed this. It would appear part of the reason
behind this is that asterisk stores the last known status of each sip phone's
Register in a database entry (which is what gets displayed in the "sip show
registry" command), and should the logical connection to that SIP phone be 
lost 10 seconds after the register, asterisk would not know that.

Although the current logic does not require a sip phone to register, it would
seem like the asterisk logic should be something like:
 a. call is attempted to sip x1234,
 b. if * knows the extn is in use, return busy, or,
 c. if not busy, asterisk attempts to contact x1234 across the wire,
 d. if no contact, return Unavailable
The sip phone could be busy since it could actually have another call in progress
with some other sip proxy other then asterisk, so I'm sure there is far more
logic required then what meets this non-programmers eye.

Rich