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.

Though I find it rather interesting that PI comes into play, though that's probably a rementent from the rotary phone era.

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Dr. Michael K. Neylon - mneylon-pm@masemware.com || "You've left the lens cap of your mind on again, Pinky" - The Brain