If traditional public telephones are to be turned into data terminals, operators must consider the social, cultural and behavioural issues. Do people really want to stand in a public place accessing the internet or reading e-mail messages?

Will people be using it for long sessions and, if so, what happens when other people want to make a quick voice call? Will people queue for a data terminal, as they will for voice calls?

Malcolm Newing, director of BT Payphones, points out that use of data terminals will not be about people downloading data to their laptop and palmtop computers. "That will go on in specific sites, such as airports and railway stations," he says. "The main use will be where people are looking for quick information or want to access a particular familiar service."

BT has 141,000 public payphones in the UK and is rolling out 2,700 Textphones. It is also providing 600 multimedia Multi.phones in shopping centres, rail and tube stations, airports and motorway service areas.

Of these, 75 per cent of usage is electronic mail to computers and short messaging service (SMS) to mobile handsets. According to BT's research, users find that retrieval is slightly more important than sending messages.

Of the 25 per cent that is used to access the internet, BT's research shows that users are most interested in maps, traffic updates, travel information, travel timetables, tourist information and weather.

This suggests that most data calls may be quite short, which is consistent with voice calls. Half of BT's 2m voice calls a day from payphones are for just a single unit of time. However, the rest can go on for quite a while, as people are using the terminals for lengthy e-mail messages.

Mike Hill, general manager for global communications at IBM, admits to getting angry stares from people standing in line waiting to use the telephone when he is using a data connection. When he was on vacation last year he had to make an hour-long conference call from Nantucket, the popular resort island.

"There was no data port so I had to use an audio coupler on a second payphone to view the slides whilst I talked on the first," he recalls. "The people on the street looked at me as if I was from Mars! I would much prefer to have used wireless voice and data connection so I never to had to leave my boat."

Mr Hill points out that whereas most of the airports in the US converted all their payphones to provide data connections, a lot of them have been converted back to voice only, with only about 20 per cent left as a data port. "This is because they make more money from a number of long distance calls than a single internet call to a freephone or local number," he explains.

Kiosks where users pay by the minute are also appearing in airports, and airport lounges are offering free data links, he says.

BT also sees text and multimedia terminals being located alongside voice-only payphones. "The idea isn't to replace every single payphone with a brand new multimedia instrument or e-mail phone," says Mr Newing. "You have to understand how many payphones you need in a particular site to accommodate the busy period, so you avoid creating queues of unhappy people."

Another problem with data terminals is the willingness of people to use them in public, where people can see what they are looking at or read their messages. "People would like more privacy, but that is also what they say about a payphone," explains Mr Newing. "The whole nature of a public terminal is that it is available and people can either overhear you or see, yet it doesn't stop people using it."

Anything BT can do, by providing sides or creating an all-in-one booth, would help privacy. However, Mr Newing points out that lack of privacy does not mean that people won't use the service.

Although Mr Hill normally seeks the lowest cost connection available, he admits that he might be willing to pay for privacy to make calls wirelessly in a quiet corner. He would also be prepared to walk into a kiosk and pay by the minute to connect to his e-mail system if it would allow him to leave a notebook computer behind.

BT's research shows that potential users of text and multimedia telephones are biased towards young people, which is also the case with both public voice calls and prepay mobile telephone usage.

"Young people tend to be out and about for social reasons more than the rest of us," explains Mr Newing. "They have greater need to be in contact in order to meet up." Also, many mobile users still use a payphone, because they haven't taken their handset, it has run out of prepaid time, it has broken down, the battery is flat, or because the payphone is cheaper. He believes that public data connections will continue to compete on cost against the new third-generation mobile networks.

An interesting aspect of the provision of text terminals is that they are suitable for use by people who are deaf or have impaired hearing. This helps those operators who have universal service obligations to meet. It also helps people who are still excluded from using the web because they do not have access to a personal computer.