You could always carry a laptop and mobile phone, even read your emails or do some basic browsing on a high-quality handset. But for businessmen and women working on the move, when they left the office there was one essential tool that couldn't come with them: PC access to the internet.

Even with a wireless LAN (local area network) card your laptop has to be within a certain distance of a source. But now mobile phone operators have added something new to the ever-expanding list of executive toys. The datacard or cellular PC card is simple. It is fitted with a Sim, placed in your laptop and allows access to the internet wherever you are. It is the final step to complete office mobility.

'It is a chance to access data any time and anywhere,' says Neil Mawston, a senior analyst in global wireless practice at Strategy Analytics. 'Anything that lets you get data more quickly will help productivity.'

It means businesses do not have staff wasting time travelling into the office to collect messages. Operators also offer a choice of connection to the internet only or to a company intranet as well. The latter can save time in jobs where stock tracking is important.

But despite the clear advantages of being able to access the web in this way, uptake of the product has been slow and covers only just over 1 per cent of laptops. With the cards selling for about £150 and connection charges erring towards the 'high side of expensive', according to Mawston, company IT departments don't have them high on their priority lists. Not yet anyway.

However, the product is still new, with large companies only starting a promo tional push in the past couple of months. And so far their mood is quite confident.

'Outlets I have spoken to have said they have been flying off the shelves,' says Ben Taylor, a spokesman for Vodafone. 'It is a great industry and it is expanding.'

According to Strategy Analytics, one million cards will be sold in 2003 and the industry will continue to grow to a peak in 2006, when between 3-5 per cent of laptops will have them. After that the market is likely to ebb away as the technology becomes integrated with laptops.

And although cost seems high, the buyers are by no means poor. 'Users are at the higher end of business,' says Mawston. 'The top 5 per cent of the organisation who tend to be quite affluent, middle aged and IT savvy.'

One reason that sales have begun slowly may have been the earlier problems of after-sales care. If your card wasn't working, who did you contact - the company who provided your card, your Sim provider or your laptop provider? To address the issue, mobile phone operators have started to take the responsibility.

'Vodafone looked at it and said this is great but needs to be simple,' says Taylor. 'Now we have the Vodafone Connect Card, which is fully supported by us. Now customers can contact us, not three different companies.' Orange provides a similar service.

The main difference between providers is their method of pricing. Most offer per-megabyte pricing that charges you when you send an email or upload a page, but Orange have chosen to offer a flat-rate system.

As businesses search for their operator of choice, some worry that the operators are failing to address the needs of differing buyers. Michelle de Lussanet, a senior analyst at Forrester Research, says: 'For mobile operators to be able to sell these things they need to know the needs of people out travelling. They need to really go in and get to know the customer requirements, to give a solution that will actually save them money.'

And that is exactly what all of the operators claim to offer: a bespoke solution to customers' needs. 'We don't just offer a broad brush,' says a spokesperson for Orange. 'We work with customers to find what their need is and then we provide it.'

Datacards are just one in a long line of devices that help people work on the move. Once the portable photocopier and fax have been invented, the only things they will be leaving at the office is the building itself.