I realize this service is not up and running yet.  If T-mobile really
plays a custom tune to a caller instead of the phone ringing, how does
this work?  Does t-mobile "answer" the call immediately and play the
tune while ringing the cell phone, or can a tune be substituted for

Well, its going to go live any time now. You can already dial *tune (or
*8863) to hear about it and attempt to sign up.
Here is some more information about it:
First 30 days free. $1.49 per month thereafter and $1.99 per caller tune.

If I were to buy a MOTO MPX220 phone and move the SIMM card inmy present
TMobile T610 phone would it work??
Dave

Any here using this phone? Interested to see how well it is holding up.
Also interested in people's view of t-mobile vs. attws/cingular. Who has the
better coverage? The maps seem to show att but I know maps can be
misleading, so I am curious as to what people think. I'm in MN so ...