4.2 is supposed to offer modem functionality over Bluetooth. The setup (after Bluetooth paring) won't complete for me (times out "Checking wireless data settings..")

I'm using

Country: UK
Operator: T-Mobile UK (contract)
APN: general.t-mobile.uk
Username: user
Password: pass (I've also tried 'web')
Automatic IP
Automatic DNS
Dial: *99***1# (I've also tried *99#)
Login script: at+cgdcont=1,"IP","general.t-mobile.uk"

Anyone got this (8700 and TT GO V2) to work?