No ringback / audio on outgoing calls until answer

[stuart.rendall]

We have been using 3CX with softphones on our LAN with a Patton 4638 connected to two BT ISDN lines for some time now, and I regularly get the following complaint:

'As often as not, when dialling a number, I get 1 double ring, then silence. This leads you into a false sense that the call has failed. Yet, if you hang on, someone will eventually answer it! But it is extremely disconcerting to have to sit through all that silence not sure if the call is ringing, or not!'

'Its getting really tiresome, as you have no idea whats happening. Is it no answer? Is it the wrong number and its not actually ringing?'

Many upgrades later, I am still receiving similar complaints.
The complaints seem to have no pattern and I have been unable to reproduce the problem.

Can anyone offer any suggestions?
Is it the softphone, the PBX, the gateway or something else?

I realise similar topic have been discussed a number of times but there appears to be no definative solution:
http://www.3cx.com/forums/no-ringback-tone-dialling-external-numbers-13513.html
http://www.3cx.com/forums/no-audio-until-call-answered-outbound-calls-14823.html#p86771

 

[RichardCrabb1]

It may be worth checking that the softphones are configured with the option "suppress early media" enabled. The soft phone might be generating ring tone at the wrong time, leading to this problem. If it is not that, you need to understand the behaviour of different types of phones (or do you only have softphones?).

I hope that this may be of some help
Richard Crabb

 

[stuart.rendall]

We only use softphones, and the 'suppress early media' option appears to have no effect.

 

[RichardCrabb1]

I think that you need to be ready to obtain logs when this problem happens. The 3CX keeps logs in a file, and what you can do is to use the backup/restore utitility to zip them to a file. As long as the date and time are known with the call details it should be possible to analyse the log to see what happened.

Also, it may be worth trying a few different types of phone - soft and hard. I have not heard of this problem with Patton gateways before, and this looks like it needs some careful investigation.

Richard Crabb