Few people live without email, and increasingly PC users are now also complementing email with a form of real-time email known as instant messaging, or IM for short. It's the online equivalent of CB radio, with users typing into a small display box on their screens to carry out quick, text-based conversations.

Furthermore, as soon as you log onto your machine, IM shows other users that you are present, making IM a unique way of indicating who is available. Although consumers pioneered such services in the early days, IM has now been repackaged for business by leading vendors such as Microsoft, AOL, IBM and Yahoo.

But just like the beginning of email with proprietary services, IM suffers from the lock-in effect. Each vendor is pushing their own service and in the main doesn't facilitate linkage to others. For the development of IM and the use of IM in business this is clearly a barrier. It's a bit like BT phone users not being able to call anyone with a cable telephone.

Now, thankfully, the walls between services are showing signs of coming down, notably with the recent announcement that information provider Reuters and Microsoft are linking their IM networks. This means that the 50,000 Reuters IM users in the finance industry will soon be able to chat with the 100 million Microsoft instant messaging subscribers. The announcement comes on the heels of similar deals to link Reuters with AOL and IBM's IM services with 60 million and nine million users respectively.

Among IM enthusiasts, it is hoped that connections like the deals with Reuters will become a trend leading to more interoperability between all the services. But Reuters IM user Colin Tennant, an analyst at Lehman Brothers, suggests it may only happen where there is money to be made: "We are pleased that we will be able to link with other IM services and I believe it shows that Microsoft is interested in linkage where there is a clear commercial advantage."

"Linking IM services is another step towards more widespread use of IM," says Michael Osterman, president of Osterman Research, a firm that tracks messaging services. "But most people are waiting to see what Microsoft will do, and to what extent it will take IM beyond text into internet phone calls and video conferencing."

Later this year Microsoft plans to launch Live Communications Server, which will allow companies to set up IM services with security and archiving built in. Osterman believes that Microsoft will be closely watched by phone companies who stand to lose a lot if IM takes on the broad role being put forward by the firm. Microsoft is also encouraging users of its chat rooms, which it is closing, to switch to its IM service. Some have seen this as a bid to boost IM usage prior to the creation of some paid-for IM services.

But despite its potential, most companies tolerate IM, rather than encourage its use. The BBC is typical in this respect: "It is available on every desktop but it is not positively encouraged. The main use is for remotely based staff because it indicates when they are online and you can switch from email to online chat very easily," says Nigel Paine, BBC head of training.

Similarly Gerard Neiditsch, executive director online services at law firm Mallesons Stephen Jaques, says that IM is less trusted than email: "I think most organisations are even less prepared to deal with IM than email. The conversational nature of IM chats is an even greater temptation to disregard the boundaries of ethical standards."

But much will depend on whether companies can adapt IM to their own needs. Reuters hopes to develop standard forms within IM chat so that a broker can be talking to a customer on the phone and taking personal details in real-time through a template within the chat window. Other developments include the ability to send out group messages safe in the knowledge that it will only go to those that are present at their PCs. Some believe that this will enable users to cut down on the high volumes of time sensitive emails that are sent needlessly to everyone on a particular list.

Reuters also claims that IM is starting to reduce the number of unnecessary calls made between colleagues and business associates: "There is no real need to face the wastage of telephone tag when you have large numbers of people on IM - it tends to streamline phone conversations," says Karl Arteaga, Reuters spokesman.

However, security experts see IM as yet another means by which hackers and virus writers can access corporate networks. Denis Zenkin, of security firm Kaspersky Labs, says he does not advise companies to use IM unless it is absolutely necessary: "IM poses a potential threat to security as it is yet another port that represents yet another door into your network. Using yet another online service makes you more open to the threat of viruses, hackers and spam."