Alert Info and Ring group problem

Hi, here is my problem :

I have a ring group ringing 4 phones. Three phones are Grandstream ones supporting Alert Info.

I’m using Alert Info in the Inboud route to select a distinctive ring when calls are coming from the external trunk.

My problem is that one of the phone, a siemens 450IP DECT phone, don’t like Alert Info. When it receive an Alert Info, it simply does not ring.

I doubt that Siemens will correct this problem.

So my question is :

Is it possible to disallow Alert info selectively for an extension ?

Thanks for your help,


I would create an extension where the Alerinfo gets added and then use the local extension:

Add the following lines so you add the header for the phones that you want to get the sip header:
Exten => 1111,1,SipAddHeader(_Alert_Info: Blah)
exten => 1111,2,Dial(SIP/100&SIP101)

Then for your dial statement you will use the Local extension and the sip extension of the phones that you dont want to recieve the alert

exten => 100,1,Dial(SIP/200&Local/1111@Context)

The above line will ring SIP/200 with no extra headers and will ring all the phones in exten 111 with the headers.