Bad audio when overseas

[Gav]

We have a number of staff members that travel overseas from our UK office.
They travel to places like Vietnam and Bangladesh.
They want to use the 3CX client on iPhones to keep in touch with the UK office.

I am receiving reports of very bad audio when they do so. Jitters, breaks in audio, etc.
Our internet connection in the UK is very good (100Mbps up and down).
The internet connections in these countries are good - good enough in fact to use facetime, which is what users are resorting to when 3CX doesn't work.

I'm leaning towards some kind of packet loss and/or transmission delay that screws the whole thing up, but really struggling to diagnose.

Has anyone got any ideas?
I'm wondering if changing IP transmission to TCP instead of UDP might help?

 

[eddv123]

UDP is the best option to use for VoIP Traffice (over TCP) as UDP does not send requiring acknowledgments of transmission etc - this works better for voice traffic: https://www.onsip.com/blog/udp-versus-tcp-for-voip

When you get these issues please confirm where these phones are connected when the issue occurs, local provider or wireless. Whenever I have experienced issues such as these in the past (customer connected to hotel wireless in a foreign country) it is normally always network related.

 

[Gav]

Yes - I've done quite a lot of reading on UDP v TCP when it comes to voice communication.
I appreciate the advantages and disadvantages of both.

It very well could be bad internet connections in those foreign countries and my theory is this could be exacerbated by UDP's lack of packet acknowledgement. So I'm now almost at a of considering TCP, albeit suffering a potential audio delay, might be the better option.

I also experienced a user who was using her iPhone in Bangladesh, ringing me on her iPhone using 3CX and suffering terrible audio quality. We switched to Apple facetime and it was perfect.
How can this be? If facetime, with its much greater data usage can manage perfect video/audio, why can't 3CX, over the exact same internet connection.

 

[eddv123]

The only setting I think you could try to make to 2 closer in behavior would be under the account settings. You have the setting "Use 3CX Tunnel when out of the office" perhaps try turning this off, be aware this will make it a direct SIP extension so you will give up the protection of 3CX tunnel.

Perhaps PBX delivers audio on the extension may improve the behavior (as a test try it).