I recently switched from AT&T to T-Mobile and have had a few issues regarding call forwarding. 1. Call forwarding will become activated even if the settings don't reflect this. It will happen at all times, and will not ring beforehand, just goes straight to voicemail. 2. Always forward is turned off, Forward when busy is on, Forward when Unanswers is on, and Forward when unreachable is on. I cannot change these settings from my phone. ("Failed to read data. Unable to deactivate call diverting when _____. Unsupported by operator.") Neither can tech support. I've tried using MMI codes to turn off call forwarding, and it has worked to some degree, the phone will work properly for several hours before the problem starts happening again. Which MMI code I put in doesn't actually seem to matter.