I have an iPhone 4 running iOs 6.1.3.
I have just switched from O2-UK to T-Mobile.
O2 supported Visual Voicemail and T-Mobile does not (at present)
I have set up my voicemail by dialling 222.
However, I want to set up the diverts (no answer, unreachable, busy) to voicemail but cannot find an option for this anywhere in the Settings app.
How do I switch these on?