Here's an interesting snippet which might interest others.
My daughter has one of these Telus branded phones but she has a FIDO SIM.
With stock firmware V10c it didn't work.
However, with the V10d upgrade, it works fine.
I seem to remember somewhere reading that one of the things fixed in the update was a "roaming" issue. Presumably whatever band was not supported before is now.
I'm a happy camper to be sure and I don't have to delve into ROMing and the like.