If vodafone or Telecom want to steal a few customers of one another they should bring out a skype phone like 3 in the UK
http://www.three.co.uk/personal/products_services_/skype_phone.omp

The plan lets you use the full blown 3g service to make calls with skype which is good if you are making international phone calls to land lines and national as well.
They still make money of text pxt messages sent on the phone.
It comes on prepayed and on a plan as well so money to be made in the plan area.

you can't send text's through skype I don't know about the receiving calls through skype side of things.

Am not planning on bringing one back to NZ with me as the mobile broadband plans are still too expensive in NZ compaired to the uk.

T-mobile who I am currently with only charge £7.50 a month for all you can eat mobile boradband with a fair use policy.

Dion