More than ever before the future of mobile phone firms is in the hands of the customer.

This is the year that mobile operators and handset makers are working hard to convince consumers to swap their existing phone for one that can handle forthcoming data services.

They are keen to get existing customers signing up and spending more on the new services because new subscribers are suddenly proving hard to find.

But experts are divided over whether the phones will prove popular and if operators will be able to squeeze more money out of their customers.

Cost curse

Simon East, former head of technology at handheld software maker Symbian, doubts that the most advanced handsets, which combine a handheld computer and phone, will be best sellers.

"These phones are far too complicated for the mass market user," he said.

It's unclear how popular new handsets will be

Roy Bedlow, spokesman for handheld maker Handspring was more upbeat.

"The vision we have is that all organisers in the future will be connected," he said. "All devices and organisers in this class will have radio in them."

Handspring has just launched the Treo 270 which combines both phone and PDA into one package.

But the relatively high cost of these futuristic handsets and handhelds could put people off.

Phones that have colour screens, polyphonic ringtones, cameras and can send long text messages and swap images are likely to cost around �200 when they go on sale. Handhelds are typically even more expensive.

Businesses may use smartphones because they could easily tie them into their corporate computer networks, said Mr East, but most consumers were happy making calls and sending text messages.

Tight fit

Mr East is now head of Cognima which makes software to help people co-ordinate address books across several different devices.

Only when the new services were tightly integrated into a handset and were easy to use would phone firms see lots of people signing up, said Mr East.

One thing is clear. No phone operators want to repeat the miserable experience everyone had with Wap - the phone data service that was over-hyped, over-sold and over, almost before it began.

"People had a really bad experience with Wap," said Gilles Babinet, head of mobile music firm Musiwave.

Treo 270: Is it a PDA? Is it a phone?

"People bought Wap because they thought they would have the internet on their phone. But they didn't and people are really reluctant to go through that again," he said.

Although now almost every new phone can use Wap, few mention it in as a selling point.

Instead, said Mr Babinet, it is being used as a hidden system for delivering new services.

"We cannot repeat the Wap story," he cautioned. "The whole industry has to be really focussed on real experiences for the user."

Almost all the mobile phone operators are improving the ability of their networks to handle data using a technology called General Packet Radio Service.

So far take-up of these services has been lacklustre, perhaps because of bad Wap memories.

Now, instead of relying on people to find data services for themselves, many mobile operators are embedding game and ringtone replacement services into phones to get people using them.

What needs to be sorted out is a way of securing the polyphonic ringtones, images and even video clips that people are going to be buying and downloading.

If people start sharing ringtones and images instead of paying for them, the plans of the operators to reap rewards from new data services could stumble.

"If we are going into the Napster mode, we will not have a business model," he said.