So bought Tmobil Sim card on St

[bollywoodmatt]

Is there any difference between unlocked ATT phone and unlocked Tmobil for straight talk byop project?

[maestroteague]

Is there any difference between unlocked ATT phone and unlocked Tmobil for straight talk byop project?

You may need to give more info on what you are attempting to do. The question is very broad. If you are asking about the SIMS, there are only two sims, AT&T and tmobile. There is no unlocked sim. If you choose unlocked sim, then they choose which of the two to send you. If you are using an unlocked phone and going on the same network (AT&T phone unlocked, using AT&T sim), then there is not really any difference in whether it is unlocked or locked. No advantage to the unlock in that situation. If you are taking the AT&T unlocked and putting it on tmobile sim, or vice versa, then you will likely have edge speeds instead of faster data. The exception to this is if you are using a pentaband phone that operates on the frequencies of both of the carriers. There are a number of threads lately that list tmobile phones that have the bands for both carriers, and you could search for pentaband phones and come up with a list also, like the galaxy nexus. But again, if you are looking for a particular scenario, we'll be glad to help if you'll let us know what you have in mind.

[paroots]

My experience suggests that there is one advantage to using a AT&T SIM in an unlocked AT&T iPhone 4. It was then possible to do the TMO SIM swap trick in order to activate MMS which I don't believe would have been possible with a locked iPhone 4.
Pete

[bollywoodmatt]

Well, last week I purchased a tmobil Straightalk Sim and in hopes I bought a 2009Sidekick lx for dirt cheap only to find I couldn't change the APN settings, so I am back to square one, and I already made the mistake of registering the Tmobil sim chip and I cannot transfer my account already to an ATT and thank you for the knowledge already will be looking up pentaband phones.
-Matt

[maestroteague]

Well, last week I purchased a tmobil Straightalk Sim and in hopes I bought a 2009Sidekick lx for dirt cheap only to find I couldn't change the APN settings, so I am back to square one, and I already made the mistake of registering the Tmobil sim chip and I cannot transfer my account already to an ATT and thank you for the knowledge already will be looking up pentaband phones.
-Matt

Two things. First, don't know why your budget it, but bang for the buck, the galaxy nexus from the google play store is 350 plus tax is hard to beat. Scond, you can in fact change your service to an AT&T sim. Of course, you'll have to order one and have it delivered first, but as soon as you get it you can switch your current service over to the new sim. Just go to the website and choose to activate a phone, then choose change my number from another ST phone. Your phone number and remaining balance of days in your month will transfer to the new sim in about 10 minutes.

[bollywoodmatt]

So I purchased a Nokia C6 because of the quadband it can use either Tmobil or ATT so will test results with it and see how it goes should be getting it by Wednesday and I appreciate all the guidance because I am tech savy but not cell savy.
-Matt