My family and I have been in Germany for a few days. (We all have Virgin Mobile pay monthly.) The roaming texts and calls between us worked fine, but there were some technicalities.
For the calls, we needed to use 0044 or +44 before each other's numbers (and deleting the starting 0). But for texts between us we didn't have to change anything. (Is that expected.)
In the end, I edited the contacts to use 0044 (I could have used +44). But now we are back in the UK, do I need to change the contacts back? Is it OK to dial 0044 (or is +44 better?) when we call each other now that we are in the UK? Or might we be charged for this?
Ttere is no need to change the numbers back, it does make them easier to recognise for those you call.
As for text messages, they do not go direct the the receiving phone, but to a " service centre number" overseas networks recognise this and forward it to the correct uk network, they move it to the correct phone number, simple stuff, but very clever.