[asterisk-users] Give "Busy" to the 3rd call on a BRI using chan_capi

[Cosmin Prund]

Hello everyone:

using chan_capi 0.7 and asterisk 1.4

Quick question:
How can I detect the number of "voice" channels (B channels) in use at a 
given time. I'd like to call "Busy" if two B channels are used on my BRI 
to give the calling customer a Busy signal.

Long question:
On my single-line BRI (two channels) I'd like to give the 3rd 
simultaneous incoming call an busy signal. I already tested and the Busy 
function works very well (I've set up one of my MSN's to immediately 
call Busy). I also tested and I'm 100% sure the 3rd call makes it into 
the box while the other 2 channels are talking, so this is not a Telco 
problem and it can be "fixed" locally. Doing this on my side of the line 
(as opposed to having the Telco issue the Busy signal on my behalf) has 
an number of benefits: (a) I don't need to talk to the Telco (b) I 
*know* who called and I can call them back and (c) In a distant future I 
might use the capi channel's ability to transfer the call to a different 
POTS line since this doesn't use the B channel.

Thanks,
Cosmin Prund