Australia's third largest mobile carrier, Vodafone, issued misleading advice to customers wanting to switch from prepaid mobile accounts to contracts, a company official has confirmed.

The company joined its competitors in advertising implementation of mobile number portability, effective from today, which allows customers - on prepaid and contract billing plans - to change carriers without changing mobile numbers.

A message on the company's Web site reads: -You will be able to port a prepaid number. A prepaid number can be ported to a postpaid service, and vice-versa."

However, a Vodafone call centre manager told ZDNet that customers who wanted to switch from prepaid to contract billing were told they would have to switch to another carrier.

They said Vodafone was only equipped to take on customers from other carriers who wanted to switch to contract billing.

The company's Web site does not mention the catch.

-We haven't gone from prepaid to postpaid yet," the manager said.

-It's from carrier to carrier, not within the same network."

-We haven't been given any information as to when that will happen."

The Australian Consumer Association's Charles Britton said the catch was confusing, considering customers were worth more to carriers when they were attached to long-term contracts.

-What a fabulous way to lose customers," he said. -It has all the hallmarks of a stuff up, rather than a conspiracy."

Vodafone later confirmed the advice given on the company's Web site was true. Customer service representatives had been instructed that the service was available, a company spokesperson said.

One mobile salesperson said customers who wanted to make the switch within Vodafone networks would have to pay for new handsets up front.

Byron Kaye is a Vodafone customer.

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