First off, thanks for looking. I recently bought a T-Mobile 7100t off of Ebay. I am looking to use it on the Cingular network. When I inserted my SIM card into the phone there is a message at the top that says 'invalid SIM Card'. Does this mean the phone is locked. I followed the instructions in the other threads in the search and when I go into the SIM Card setting, I can't enter MEPD. What do I do? TIA

When i first got my 7100t from ebay, i had an AT&T sim card, and i got that same error, As i figured, the phone was locked.
The 7100 and the 7105 are made exclusively for Tmobile.
I had a lot or problems unlocking it. So i just gave up and signed up for tmobile.
its worth a shot though

see if you can get it unlocked

I have a 7100-T...unlocked.

pm me if you are interested.

-simpson

If you call T Mobile they will unlock it. Its not a free service, but its not too bad. £30, I think, was the last I heard.

I think its free if you've had the phone for 12 months, but if you bought it off somebody else you probably have to pay.

fishake - you are kind of close, well a little, but not really.

T-Mobile will unlock a phone if you are a customer of theirs, have been in good standing for at least 30 days, and have not unlocked another phone through them for 90 days.

Since the OP didn't buy the phone through T-Mobile and does not appear to be a customer, they will not unlock it so he can use it on Cingular.

Cimulation, go to one of the commercial unlockers like GSMPhoneSource and see what they can do.

Yes they will send you the unlock code for free. I got my 7105t unlocked free.

They sent you a code for a BlackBerry you bought off of eBay?