Att cell phone techinque support customer service

Contact your service provider help desk

Depends on the phone model. If it has support for Att radio bands then theoretically yes. But it depends if the root. Bootloader unlock and custom radio firmware exist. Get in touch with a phone carrier flasher. Viper32 at kittywireless is a good start.

ATT ...well they used to advertise they had the best signal....and they once did....and continued advertising the same thing and the lie became a sorry joke on customers as the service got progressively worse. Now...that's the real history...so ATT has credibility problems and can't be trusted no matter what they claim on the subject. Some areas...just not well served.

A cell phone PUK (PIN unlock Key) is connected with the SIM card, not just the cell phone itself. To obtain the PUK, you need to contact the service provider of the SIM card.
AT&T's customer care number: 1-800-331-0500 or through att.com/myatt T-Mobile's customer care number: 1-800-866-2453
If you use a different carrier, check their website.

Att GoPhone has a nokia 2720 on sale at their website.
You do not have to purchase a refill card, this option can be remove during checkout.
If you are an att customer, you can just install your sim card and the phone will work.
View this website.

http://www.wireless.att.com/cell-phone-service/cell-phones/cell-phones.jsp?wtSlotClick=1-004L9E-0-2&allFeatures=on&feapaytype=pyg&allManus=on&rel=nofollow&rel=nofollow&allTypes=on&startFilter=false

You may have to call TMobile Customer Service to get it to work. I had to do that with Tracfone.

Call Yahoo Technical Customer Support Number USA 1 844 414 4869

If you have an AT&T account:
FOLLOW THESE STEPS TO NETWORK UNLOCK SAMSUNG SGH-A737

GET THE UNLOCK CODE FROM ATT CUSTOMER SERVICE 18003310500

1. REMOVE SIMCARD AND TURN ON HANDSET
2. The display will read INSERT SIM CARD
3. TYPE #7465625*638*--------# .THE DASHES ARE YOUR 8 DIGIT UNLOCK CODE OBTAINED FROM ATT CUSTOMER SERVICE.
4. U WILL GET A MESSAGE SAYING NETWORK LOCK DEACTIVATED.

after the second asterisk, you'll see a dash ("-") on your screen instead of the number you type.

I also have a x426 from 2003 and it wont work with the new ATT sim cards either, This is because of the Cingular/ATT merger which created a new network. The older original ATT phone must be unlocked to use a sim card from the new merged network. Try calling ATT Mobility customer service and request the subsidy unlock code. They are required to give it to you upon request, but it takes several days usually to get the code. I know because I used to work at a ATT call center.