The PhoneBoy Blog

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T-Mobile Prepaid and an Unlocked iPhone 3GS

Something I’ve been meaning to try out for a while, but haven’t had the chance to, was to see if I could make my iPhone 3GS on iOS 4.2.1–jailbroken via PwnageTool 4.2 and unlocked via ultrasn0w via Cydia–work on a T-Mobile prepaid SIM. Specifically, on Pay As You Go, not on one of their data plans.

There are some obvious limitations with this: namely T-Mobile’s coverage, lack of compatible 3G on frequencies that my AT&T iPhone can use, and, well, being jailbroken. Considering how little in practice I actually need data outside of the range of WiFi, the pricing–$1.49 per 24 hour period–makes it a limitation I can deal with.

Jailbreaking and Unlocking your iPhone is a bit outside of the scope of what I’m writing, but you can look at a somewhat dated (but still relevant) guide from The iPhone Blog Forums.

After unlocking, you’re going to want to turn off 3G since the iPhone is not compatible with T-Mobile’s 3G. This can be done in Settings > General > Network. Also here is the Cellular Data Network settings, which you will need to set as follows (note if I don’t list the field here, assume it is blank):

Cellular Data:

  • APN:


  • APN:
  • MMSC:
  • MMS Proxy:
  • MMS Max Message Size: 1048576
  • MMS UA Prof URL:

There’s one other thing you are going to want to download in Cydia in order for MMS to work correctly. Type Manage > Sources > Edit, then Add. The APT URL you want to add is Then click on Search and look for T-Mobile US MMS Fix. Download and install this, which will reboot your phone.

After this, MMS sending and receiving should work. To use EDGE data service, you will need to fire up a web browser and ensure you are not on WiFi. Any web site should redirect you to a page telling you do not have data. You should be able to click through and order a daypass, which gives you 24 hours of data access.

I tried a number of applications: maps, email, Twitter, Boxcar, and of course a web browser. They all worked well, albeit slowly on EDGE. I confirmed I could send and receive MMS between an AT&T and T-Mobile SIM also.

There’s some verbiage in the terms and conditions about being throttled if you use more than 30MB of data in a 24 hour period. The reality in this case is, it’s EDGE. It’s already pretty slow.

#Cybersecurity Evangelist, Podcaster, #noagenda Producer, Frequenter of shiny metal tubes, Expressor of personal opinions, and of course, a coffee achiever.