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

John Todd jtodd at loligo.com
Tue Jun 17 12:03:49 MST 2003

>Hi Todd,
>John Todd wrote:
>>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.
>If this is not possible within asterisk, is there a way to change 
>the ring of a line on the phone itself?
>Is there a way to insert a variable into an outgoing INVITE?

There is a pending patch that Mark has been given (by "km-", whose 
real name I don't recall) that will add this "distinctive ring" 
feature to Asterisk, by setting a variable before sending a call to a 
SIP outbound channel via Dial.

However, "distinctive ring" is really only what I would call a 
"double ring".  It does not in fact change the ringtone of the phone, 
but instead tells the phone that it should ring twice in rapid 
succession with the same ringer.  So, when the header is set, you 
hear "ring,ring.....ring,ring" instead of "ring.....ring.....ring"

This is still quite useful to identify "special" callers.

The patch, by the way, simply adds an RFC-described header to the SIP 
INVITE, which is called "Alert-Info:"   The Cisco 79xx looks for a 
numeric setting, and any number will set the distinctive ring. 
However, the RFC describes this header as being any text string, 
including URLs, so that some phone implementations could do something 
like this:

Alert-Info: <http://www.foo.com/ringers/trainwhistle.wav>

I'm waiting for those features to be implemented in the phones; the 
Cisco does not support anything like that right now.  :)


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