Callers only get one ring when they dial me

[Oliver85]

I currently have an iPhone XS and ever since I bought it, when people ring me they get a single ring in their ear and then it goes silent, however my phone actually continues to ring.
What happens then is I get people thinking the call hasn’t connected so they continue to hang up and dial again so I end up with several missed calls.
I have tried all the usual ideas that CS give you by removing the sim, changing setting etc but to no avail.
This is such a frustrating issue as I’m sure you can appreciate. I’ve read the odd post with other customers of O2 experiencing the same issues but no one ever says what eventually happened. Please can someone help!

[MI5 · Accepted solution]

@Oliver85 

As you say there are a number of other posts with the same issue.

It is thought to be an account issue but customer service need to refer your case to tech support Guide: How to find help & contact O2 

[jonsie]

It might be as well to try a new sim card if you haven't already.

[Oliver85]

Thanks