Choppy audio on VOIP

[#1]

We're having a problem with a friend in Budapest using Zoom, Skype and other platforms.

Her voice is choppy (usually quite rhythmically waxes and wanes). She has no difficulty with ours. We use Zoom a great deal for transnational multiple user calls and don't encounter this problem; we have tried Skype, without success.

Our internet speed is generally between 28 and 45 Mbps download; 18 upload. Ping varies between 13 and 21. Jitter 4ms. Wifi speeds fine. The calls do not drop.

My questions -

Is this more likely to be a problem with her hardware and IP? Is there anything I can ask her to do? She has occasionally used a smartphone, but mostly it's laptop.

If its our problem or a joint one, what can we do?

I had thought of disabling video at one or both ends: but I'd rather not if possible.

We don't use voice mute. It's not something that's been necessary on other calls. Perhaps we should? 

Any suggestions gratefully received. Thanks

Apologies, this should really have gone in Fibre, not ADSL

[#2]

Moderators Note
This topic has been moved from ADSL Broadband to Fibre Broadband.

[#3]

Just making the wildest guess, I would suggest an issue at her end.  I don't know about Budapest but typical end user broadband type services have a slower upload than download speed.  Her audio and video to you is going out on her upload direction, and you're receiving it as download. 

Try getting her to disable video as a test, and see if the audio quality improves.  Video uses much more bandwidth.

I may misunderstand but it sounds like you don't have issues with other callers, again this points a tentative finger at her end.

[#4]

Thanks. Yes, it looks like I'm going to have to try disabling video.