The only critique I have on that is that some phones do have 'q' and 'z' (on the 7 and 9 respectively). While chances are that for the problem at hand, adding q and z won't increase the word set that much, there's still a possiblity of doing so.
in reply to Re (tilly) 2: (Golf) mobile phone numbers - words
in thread (Golf) mobile phone numbers -> words
Though I find it rather interesting that PI comes into play, though that's probably a rementent from the rotary phone era.
Dr. Michael K. Neylon - firstname.lastname@example.org
"You've left the lens cap of your mind on again, Pinky" - The Brain