StraightTalk data plan issues on unlocked GSM iPhone 5
Bit of background first...I have an unlocked iPhone 5 (GSM) and have signed up for the $45 StaightTalk unlimited plan. I ordered a sim and cut it down to nano size. The sim card prefix shows that I got an AT&T sim as expected (first 6 digits are 890141). When I install the SIM, I do momentarily see "AT&T" in the the upper left of the screen before it switches to "HOME 4G". Voice and SMS texting are working. So this makes me believe I'm using AT&Ts 4G network.
Things get weird when I try to get data working. I initially tried the profiles at (unlockit.co.nz) which set the APN to att.mvno without any success. I then learned that StraightTalk itself has iPhone APN profiles you can install at (m.straighttalksim.com). When I install the AT&T APN profile for iPhone (APN set to att.mvno) data still does not work. However, when I try the T-Mobile APN profile for iPhone (APN is set to wap.tracfone) data DOES start working.
Can anyone help me understand why the T-Mobile APN settings are necessary on an unlocked iPhone 5 using an AT&T Sim card? Does this mean I'm using AT&T cell towers for voice and T-Mobile cell towers for data? I'd much prefer to be using the AT&T 4g data network since it has better coverage throughout the western US.
Any insight would be appreciated.
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