This is a strange one.
I've a laptop with Windows 8 and an integrated mobile broadband modem, and XT sim with data loaded and tested working from a phone.
Problem is I can't connect with the internet.telecom.co.nz APN, but I can with either the wap.telecom.co.nz or direct.telecom.co.nz APNs.
This is most bizarre.
To clarify, with the internet.telecom.co.nz APN the stupid charm window with the list of network connections does say mobile broadband is connected, but the usual windows "network & sharing centre" window shows no connection.
The standard network connections window shows the mobile broadband card as disconnected contradicting the charms status.
All APNs works fine from when putting the sim in a phone.
I'd be interested if anyone else can reproduce this.