brightwell - there may be another reason for verification code, which concerns tracking a mobile (from what I've heard, you could use the internet to show a map with various locations when the phone had been 'interrogated').
I don't have any web links for these services, but again, without entering the verification code, it doesn't work - in the case of monitoring, the chap I heard on radio said that his service sent out regular reminders/warnings that monitoring of location was active {though the complaint was that monitoring might be active for days before the phone user got one of these messages}.
I will see if I can find some web links to UK services offering tracking... Oh dear, found about half a dozen so have not checked them all, yet.
On vodafone there's a service called ZYB which allows for backing up messages etc, but as I'm not a customer, don't know how close this comes to 'bluebook' on O2.
Seems a bit creepy, must admit, and like njmomof1, can see wanting to limit costs, but not pry into content.