Due to area code, phones don't match numbers calling with numbers in the Corporate Directory. We have a corporate directory set up, but any entries there don't match the numbers that call us, and the names from the directory aren't displayed. I've done some testing with the local directory; I'm very sure this is because it sees the number with an area code as different from the same number without it (For example, it would see 01234 567890 and +441234 567890 as two different numbers and not match them) But attempting to edit the corporate directory with 0's instead of +44s results in an error, so we're a bit stuck at the moment.

On the deskphone,
Directory -> Local Directory -> All Contacts -> Add
Entered my phone under "Richard Mobile" with the +44 area code.
I attempted to ring it, and the number displayed was a 0, but it didn't display my name.
I went back into the directory and changed it from +44 to 0
If you attempt to ring it again, "Richard Mobile" will be displayed alongside my number.

This means that, in theory, I could sort it by accessing each phone's web API and uploading a CSV I've made with 0s instead of area codes. I've tried this with one or two phones already, and it has sorted it.

The issue with doing it this way is that if we have any changes to staff, such as new starters or leavers, I would have to manually access every phone to make the changes rather than simply editing the corporate directory one time. So it's very much a bandaid solution, and I'd prefer to have the corporate directory sorted and working, as that would make it much easier down the line.