I've got another 3 rings for you..
I have seen on 4 different phones and 3 operators over time the same happen again and again:
Phone rings once, then cuts over to voicemail. No user action required, full signal and normally excellent reception when making a call.
Result: twice the revenue!
Revenue 1: voice box call to user
Revenue 2: user calling voicemail.
To be applied to users who mainly make short phonecalls.
Enhancements to revenue: use voice help menus that are really explicitly going into all the wonderful and staggering features that you will get when you press, 1, 2 or 3, and no f*cking way of shortening them as having the nerve to press any key -you guessed it- results in them starting from scratch. All that effort has but one real reason: getting you past the magical 1 minute charge barrier so that whatever you do you get stung for two minutes.
Phone companies may have invented the rip off, but mobile phone companies sure have soldiered on with developing it into an art form..
OK, I'll lie down now..