Key Points:

Australian phone company Telstra is less than 100 days away from switching off its old CDMA mobile network.

The CDMA system has been in place in some country areas not covered by the GSM network.

Most of Australia is covered by GSM - the same as Vodafone uses in New Zealand.

The company has spent A$1.1 billion ($1.3 billion) replacing its CDMA network - the same technology as Telecom's mobile network.

Telecom mobile customers at present use Telstra's CDMA network when roaming in Australia, but from the end of January will need to take a WorldMode phone.

These work on Telecom's CDMA as well as Telstra's new GSM technology.