Phone Number Mystery

[TheMacintoshLady]

I have been using my new Mac just to fax from OS X...it's been working OK 
I guess, but I have a new mystery I can not solve.

I just added another name - a business office that is three letters. I 
put it in like this XXX and the number is out of town and I must dial 
1XXXxxxXXXX.
So, I tried entering it without the 1 and adding it in the window where 
it says Use Prefix, tried without the first three XXX and adding1-XXX and 
still it is the ONLY number that WILL NOT drag into the window. Is there 
NO other way to enter a number in there??? What could be wrong?

TextEdit has crashed a zillion times in the process.

I can honestly say I have NEVER had Simple Text crash on me and I code 
huge websites it in..<sigh>