[Asterisk-Dev] Distinctive ringing on Cisco 79xx - useful feature

[John Todd]

I've run across the "feature request" for distinctive ringing in 
three different locations/bids now, where Asterisk is being compared 
to "traditional telephony" using SIP.  Thus far, I haven't been able 
to answer "Yes" but it looks like with only a minor hack, I could 
check off that box.  It's not a show-stopper, but it certainly would 
be handy.

Interesting feature on the Cisco 79xx phones that you can activate 
distinctive ringing with an additional SIP header.  It would be 
really useful to permit this as a set-able variable in a dialplan, so 
that different inbound callers might activate different ringtones, or 
the same ringtone in a quieter format based on time of day.


 From the SIP Administrator's Guide:

http://www.cisco.com/univercd/cc/td/doc/product/voice/c_ipphon/sip7960/sipadm42/sipadm42.pdf

Distinctive alerting
If the INVITE message contains an Alert-Info header, distinctive 
ringing is invoked. The format of
the header is "Alert-info: x". The value of "x" can be any number. 
This header is received only by
the phone and is not generated by the phone.
Distinctive ringing is supported when the phone is idle or during a 
call. In the idle mode, the phone rings with a different cadence. The 
selected ringing type plays twice with a short pause in between. In 
call-waiting mode, two short beeps are generated instead of one long 
beep.


JT