Below is a screen shot from my iPhone which is on the T-Mobile network.
APN: general.t-mobile.uk
Username: user
Password: one2one
MMS: http:/mmsc.t-mobile.co.uk:8002/
MMS Proxy: 149.254.201.135:8080
Voicemail
T-Mobile’s voicemail setup is a little different from other networks: in addition to your mobile number you are also assigned another unique number for voicemail.
If you don’t already know your voicemail number, do the following:
Dial: *#67#
The iPhone uses push voicemail, in order to “re-program” it for T-Mobile, you need to do the following replace 123456789 with your unique number as obtained above.
Call: *5005*86*123456789#