I recently moved to San Francisco with my iPhone 4. My iPhone is factory unlocked as it was bought in the UK. I went into the AT&T store and i wasn't a fan of the plan they were outlining for me, so i went across the street to the T-Mobile store.
I got a T-Mobile plan, and they nicely cut the SIM card up for me so that it would fit into the iPhone 4. Once my phone was activated, i managed to get rid of the voicemail notification.
I couldn't get FaceTime to work on T-Mobile.
One night while i was talking to a friend, he told me to try turning FaceTime on again. Previously this had not worked, so i wasn't very hopeful. However, this time it worked. I didn't understand why, but i made and received several calls with FaceTime working perfectly.
Tonight, i popped my old O2 SIM card into my iPhone to check on my messages. After i put my T-Mobile SIM back in my phone the FaceTime buttons were gone.
Here's the list of actions i took, and i now have working FaceTime on my iPhone 4:
- Turn phone off and on—can't hurt right?
- Ensure that you have WiFi, and the FaceTime switch is turned off.
- Go into General, then Network. (My settings are Enable 3G: Off, Cellular Data: On, and Data Roaming: Off)
- Go into Cellular Data Network.
- For the Cellular Data APN enter epc.tmobile.com.
- For the MMS APN enter epc.tmobile.com.
- For the MMSC enter https://mms.msg.eng.t-mobile.com/mms/wapenc.
- For the MMS Proxy enter 126.96.36.199:8080.
- For the MMS Max Message Size enter 1048576.
- For the MMS UA Prof URL enter http://www.apple.com/mms/usprof.rdf.
- Go back to the first pane in the Settings application.
- Restart phone.
- Go back into the Settings application, go into Phone.
- Switch the FaceTime switch to On.
After this, it should say "Waiting for activation" below. About thirty seconds to a minute later, mine changed to "Your phone number will be shared with people you call with FaceTime.", which i believe means that it is working. I tested via FaceTime on my Mac, and that was fine.
This seems to have worked for me twice. I can't guarantee it'll work for everybody.
To verify, here is a picture of my Settings application once this has worked: