My device always shows my region correctly as United Kingdom. I have altered to various other regions then back to UK and it fixes the problem but only temporarily. I've noticed that there are several different iOS levels quoted. I'm om iOS 13.2 and in the process of currently updating to 13.2.1 - forever hopeful of an Apple bug fix, Like an earlier post I was also out of the UK when I updated iOS, in my case to 13.1
I just joined here to say that I am having exactly the same problem with the phone number formatting. I have a new iPhone XS and have changed from EE to Virgin as of 3 weeks ago. The dial assist problem came up to start with but have sorted that thanks to the community posts above, but the phone number formatting is a regular nuisance plus it also then doesn’t sync to your contacts so any messages or phone calls just show as a phone number. I haven’t been out of the country at all. Is this just a Virgin issue? I didn’t have this problem with EE and my old iphone6. Can I report it somewhere?
Todate, Apple claim it's a “Network Settings” issue however, the network service provider (in this case Virgin), claim it’s an issue created by Apple updates. Neither seem prepared to assist with a diagnosis, let alone a fix.
We have 2 iPhone SE's in this house, both with Virgin SIMs and both exhibited the phone number formatting problem. One phone has not seen the problem for a couple of weeks after the the usual suggested fixes. The second exhibits the problem several times a day. We are now both at iOS 13.3.3 and still trying to find what is causing the issue. Today has been problem free up to now because I have closed all Apps as soon as I finish using them in an attempt to determine if an App (s) is the cause. Almost at the stage where I will reset then re-install.
Just thought I would add to the post from @Emily_G to say I am still running my iPhone 8 on iOS 12.4.1 as I have read some pretty negative reviews of the iOS 13 updates. This may or may not shed some light on why the switches between UK & Belgium worked for me but not others?
I am certain the problem originated with the Virgin message to update settings though, even if the software running has an impact on the solution. Definitely would never update any settings whilst abroad again.
Can confirm that I have been using the advice given ie switch phone settings language to Belgium and then back to the UK which does solve the problem. But as other people up thread have mentioned, sometimes it seems only short term and it can revert again. I've found that if I turn my phone off (as I did in the theatre the other evening), when it's turned back on again the phone number format has reverted to continental again. Whilst I appreciate that there is a fix for it, it does seem ludicrous to keep having to do it. My iphone operating system is up to date and I did not have this problem with EE until I switched to Virgin 3 weeks ago.
Emily - I have tried everything recommended after disabling dial assist. Up until yesterday I was changing the region up to 6 times a day. I am currently closing every app after using it with the result to date that I only had my phone numbers wrongly formatted once. Still early days but I am open to any NEW suggestions.