There are a few gotcha but I suggest the following will work:
1. Use the software that comes on the supplied CD-ROM from Telecom
2. You must start the WModem software on the phone before plugging it into a USB port on your computer.
Unfortunately you then have to ring the 0800 116 110 number and choose option 2 or try to get a human and ask to speak to the Telecom Advanced Wireless help people. I spoke with a person called Raj who asked me to dial a series of numbers starting with the # key and then make some changes to the settings and reset the phone. Regretfully I did not note these - will try to get them and post here for others but if you persist Telecom do have the solution. Since doing this the phone has worked fine.