Call Waiting support?

Hey everyone,

I have asterisk connected to a gateway (sip trunk) to make outbound calls.
The problem is that when one extension is on a call, another extension calling to it doesn’t hear the call waiting sound (fast ringtone) but a normal ringback sound (as if the extension wasn’t on call).

To put it in simple words - if extension A and B are on a call, a call from extension C to either A or B results in extension C hearing a normal ringback sound instead of a call waiting sound.

What is the problem? where should I start looking?

A note: I have connected a SIP phone directly to the gateway (bypassed asterisk) and this way the SIP extension does hear the call waiting sound.


Seems to me that Asterisk does not correctly produces the signalling tones.
Do you have the correct settings in indications.conf ?

Or Asterisk does not interpret the signalling correctly. When you hang your SIP-phone directly to the SIP-trunk, it is the SIP-phone that interprets the signalling and produces to you the call waiting tone.

Now if Asterisk does not send the correct signalling to your SIP-phone, it can not produce the correct sound to you.

You need to debug. Insert in your dialplan something like
to see what Asterisk experiences on the SIP-trunk.
Should give you ‘Busy’…

I don’t think this is related to indications.conf as the connection of the Gateway to Asterisk is via a SIP trunk.

I have continued to diagnose the problem and noticed that the Gateway sends 183 with sdp and then 180 with sdp, as a result Asterisk sends 180 Ringing to the SIP extension registered to Asterisk.

That seems to be the problem since I would expect that Asterisk, upon receiving the 183 with SDP or the 180 with SDP will open up a media channel to the extension (early media) but it doesn’t.

Any comments on that?


The file is pretty big and extensive and has some configuration of my organization phone network. Are there relevant parts to post rather than pasting the entire file?

By the way, I’m just wondering how this is related to the dialplan as it seems to be an issue with asterisk dealing with SIP messages in a much lower level…


This is the way Call Waiting works everywhere. The party placing the call to a busy telephone hears normal ringing. The called party normally hears a beep overriding the conversation. I run Asterisk with analog telephone sets connected to Grandstream ATA devices. They work exactly as you describe. Beeping at the calling party would serve no purpose. It’s the called party who needs to know about the incoming call, no?