The My Number field should auto populate providing the carrier entered the number into the correct slot, if not it will show as Unknown. That happened to me when I got voice on my BB, it was unknown for a while then it changed to my actual number on its own.
But the EA is usually the only way to transfer the data, I've heard of another but I can't think of what it is. I could also be a tard and completely wrong
As long as the number shows in the phone app it should sync to the BES, if it doesn't show there it will never sync until it shows.