Which servive for blsckberry

They both work with the Blackberry phones. A friend uses T-Mobile with his 8800 and I have AT&T with my 8300. I get reception when he cannot, but not vice verse. I used T-Mobile several years ago and found their coverage spotty in the cities I was visiting at the time (CLT, SFO, and SJU). Cingular/AT&T had great coverage in those cities. YMMV

AT&T usually works well overseas. Have used it in China, South Africa including a safari camp, much of Europe, Canada and Mexico. Almost always has phone available. Data was also generally good but sometimes had to manually change networks. Domestic service for me has been above average. Have never used T-mobile.

You need to somehow find out which one has a stronger signal in the areas you spend the most time. That will be the most important difference between the two. Don't believe the carrier maps - talk to people with each service.

check out howardforums for cell phone questions.
I thought Tmobile piggy backed off of AT&T towers in some areas? And since Tmobile on works on 1800/1900 MHz, where AT&T runs dual band 850 & 1800/1900 I would think AT&T would usually have better coverage (if your phone supports both signals)

I think that T-Mobile data plans are considerably cheaper than AT&T's.

I used to have AT&T, now I have T-Mobile. The reasons I switched are:

AT&T charged me for $72 worth of calls I didn't make, and wouldn't credit them back even though their own records show they took place 1,200 miles from where the phone was ten minutes earlier.

T-Mobile international roaming is 99¢; AT&T charges $1.29 unless you pay them $5.99 per month, in which case it's 99¢ (and if you have the service turned on for one day in a billing period, it's still $5.99).

T-MobileWeb (unlimited surfing, including Gmail) is $5.99 per month; AT&T charges by the bit.

If both carriers have adequate coverage in your area, I can't think of a single reason why you should go with AT&T. As of this writing, if you sign up for T-Mobile service with Wirefly, you can get a $400 quad-band Wing PPC for free! Click here.

If you go with TMO, you might want to wait a couple of weeks for the rumored Hotspot@Home enabled BB.

My choice would be T-mobile. Customer service and billing are vastly superior. I also find voice quality superior and use both services regularly (T-mobile with an E65 and AT&T with an N75/iPhone.)

Before you do anything though, go to Target/Wal-Mart and invest $20. Buy a prepaid package from the carrier most attractive to you. Make calls and try the service out in the areas most critical to you. If service sucks, spend another $20 and buy a package from the other carrier. Dunno about T-mobile but AT&T sells the junky Motorola C137 with $10 in airtime credit for $20 at Target. Sure you have 14-30 days to return and cancel but why spend all the time doing the credit check, etc when this is so much easier? You also then end up with an oopsie phone you can shove in a drawer and use as needed.

Or just sign up for a new line with both carriers. They each give you 14 days to return for a full refund (less the airtime you use).

30 days in California.

I've used both and by far my choice would be T-Mobile for the following reasons:

- plans are MUCH cheaper
- customer service is MUCH superior

I have not been anywhere (with the exception of the basement of a building in downtown Manhattan) that my t-mobile blackberry did not work.

I have to admit that I am sorry to see ATT go down in flames the way they have. I was with them for years, starting with my first ATT "one rate" when they first started it, but IMHO they have forgotten who their market is, what customer service is, and how to compete and they are now just trying to survive based on their brand name....

Oh, yeah. Wirefly also has a T-Mobile Blackberry deal.

Walgreen's is showing a Nokia with prepaid T-Mobile for $30 this week.

I use T-Mobile and have for the last several years. I have found T-Mobile's coverage maps to be pretty accurate, at least for some of the mountaineous areas in the Front Range. There are several particular places where I know what my phone's signal strength is (or where there is no service) and that agrees with what TM shows when I zoom in.
http://www.t-mobile.com/coverage/

When roaming, GPRS has worked for me on AT&T and on USA 430(?), IIRC. It did not work a few weeks ago when I was roaming via Sprint (which surprised me that I was able to roam on a Sprint network at all since I did not think Sprint and T-Mo were using the same technology; shows how much I have been keeping up).

In the US, T-Mobile uses 1900, but has roaming agreements with some carriers that use 850 (including AT&T in some places). AT&T uses both 1900 and 850.

900 and 1800 are used in many places outside of the Americas.