I'm very seriously thinking about switching from ATT to Straight Talk with the ATT compatible SIM. I have an ATT HTC One, I'm not under a contract, and I want to port my phone number. I've looked at various options and this seems like the best fit. Has anyone else attempted this exact conversion? Are there any pitfalls, weird configurations, ect that I should be aware of before making the switch? So far the only thing I've been able to find is that it can be tricky to get picture messaging working. I'm thinking with the ATT compatible SIM I shouldn't need to get the device unlocked, that's correct, right? Are there any other possible issues I should be aware of?
I recently ported one of my phone numbers from ATT to Straight Talk. I have an HTC One that is in the process of being unlocked but is locked to ATT at this time. I used Straight Talk's BYOP program and the setup was easy and everything seemed to be working fine until MMS (picture messaging) stopped working after the most recent Android update to 4.4.2 KitKat. I'm not sure if that has anything to do with the inability to send MMS messages but it is what it is.
In my experience with Straight Talk, their customer service and tech support is absolutely useless and because the HTC One is not ne of their phones, they do not provide any type of support. That said, even if you bring a phone to ST that is compatible such as the Galaxy S4 which ST now sells, because it was not purchased from ST directly, ST limits the SIM card's ability to take full advantage of the network to send MMS messages.
Take a look at the hundreds or thousands of forum postings for all sorts of phones that can't get picture messaging or data working. So far, I'm not impressed.
Also, don't bother using the Straight Talk Wireless Forums. The ST moderators do not allow publishing of anything derogatory towards their service and they do absolutely nothing to help solve problems, just read from a set script and then blame any issues on "your phone's limitations."
I had hoped to save a significant amount of money switching to ST and I even have a second BYOP purchased for the wife's Galaxy S4 but I'm not sure I'll use it now considering that the limitations on the phones are imposed by ST.
Good luck, hope this helps.