I have a Motorola cell phone with a one year contract (currently in
the 7th month) with Cingular wireless.  This phone does have a SIM
card.  I don't particularly like this phone and its performance is
less than adequate.  I want to get a new phone, but I cannot get one
from Cingular until the 9 month time of the contract without paying
full price.  I can find a phone on eBay or another location for much
cheaper.

Is it possible to buy *any* other phone and have it be compatible with
the Cingular network?  How can I avoid dealing with Cingular to get
this new phone to work on the network (I've read several things about
locked/unlocked phones - not sure if this is relevant)?  Will Cingular
even know, and, if yes, will they care?  And, can I keep my number?

Thanks!

You should be able to take your SIM (Subscriber Identification Module)
out of your existing mobile and pop it in the new one.

This will allow you to use your existing Service Provided but only if
your new mobile is 'unlocked'.

When buying a new mobile do make sure that it is unlocked or easily unlockable.

Oops

For 'Provided' ... (below) ... substitute 'Provider':

This will allow you to use your existing Service Provided but only if
your new mobile is 'unlocked'.

epsteada-ga:

You'll have to get a GSM phone that supports dual band (or tri-band)
and the  frequencies (bands) supported must include 850 MHz and 1900
MHz for it to be usable on the Cingular network in the USA.  If you
get an unlocked phone with those capabilities, you can just switch
your SIM card to the new phone and it should work fine (read set up
instructions in the phone manual to set it up) with the same phone
number.  You'd find the unlocked phones are usually sold at a higher
price than the ones that come with a phone company contract (you can
check prices for specific models on www.google.com on Froogle.

--
I am not an official GA researcher.