[apovey]

I have a Blackberry Bold 9900 which I am using on the Vodafone UK network.

Is is possible to change the number of rings (length) before the caller gets diverted to voicemail?

If so, how?

[aiharkness]

Take a look at Increase amount of rings before voicemail - BlackBerryFAQ

[Dubdub]

That is gennerally a carrier setting, as noted in the FAQ article. You should call your carrier for help.