UPDATE: Sept 27 2013
see WARNING: Straight Talk and Net10 SIM Swap with iOS 7.0.2
UPDATE: Sep 22 2013
I have an new guide How to Setup Straight Talk Wireless Data and MMS for your iPhone running iOS 7 check it out for more details.
I am working to get my Net10 guide finished as well.
A reader pointed out a consistent way to SIM swap and get into Cellular Data Network. I was having a hard time with it on iOS 7. This worked very well.
1. Put in the TMobile SIM
2. Go to Cellular Data Network with the TMobile SIM in
3. switch to the notes app.
4. insert the Net10 or ST SIM
5. wait until the iPhone recognizes the Sim
6. double tap home
7. switch to settings with CDN still open
8. enter your APN values
9. watch out because the iPhone ail change them on you
10. back out of CDN
11. restart the phone