dual ring back when dialing external numbers

[wiggum123]

So we have a odd situation when users dial out. Firstly let me explain our setup;
ISDN Gateway - Beronet berofix
This goes across an intersite link between 2 offices so goes through 2 firewalls
3CX server sitting on a windows host connected to our office LAN
Yealink T22's Connected to our office LAN

Also, I am unsure of the terminology for what I am having issues with. I believe it is called ring back but its the ringing you hear when you dial a number. If this is incorrect I apologise but for continuity I will refer to it as ring back!

Once a number is dialed the standard English ring back is heard, a few seconds after this a second ring back is heard, dependent on which country you call the correct ring back is heard in addition to the original one.
Now I imagine it is our gateway which is sending this second delayed ring back but why are we hearing both at the same time? I can try and record it and attach if none of this is making any sense!
Anyway, its annoying the hell out of me and I dont have enough knowledge to fix it!

 

[wiggum123]

Nobody else having this problem?

 

[leejor]

I have experienced this when using the 3CX phone, which I believe is set for "early audio". It's been a while since i went through the settings so the name may be different. It would seem that something, either 3CX, or perhaps another device, is providing ringback rather than silence until such time as an audio path is established (SIP message confirmation). in many cases this is preferable as too long a period of silence may cause the caller to hang up and try again.

On the 3CX Phone I do not believe that the ringback tone can be changed away from the UK type. The tone you are getting might be changeable, but you'd have to confirm where it is coming from. Calling out on the PSTN gateways that I use, results in silence (sending DTMF barely audible) until the gateway has completed sending the DTMF out on the phone line, at that point audio is cut through and ringing can be heard. That being the case, you might want to look into the "region" settings on your gateway. If the ringback is originating from that device there may be a way to provide something closer to what the provider sends back so that there is not as noticeable a transition.