Yet defining SMBs in ways other than size is often difficult.

Barrow at Cranfield, who is selling to companies with £2m to £5 million turnovers, says: "You can buy lists which split SMBs by size, by sector and by geography, but that is about it. You canÕt buy lists which indicate behaviour, such as whether they are high growth, life-style or have a heavy IT spend."

"But you really have to do the intellectual heavy weight-lifting if you want to crack SME markets."

An academic who has studied SMBs internationally for two decades, Barrow knows of no academic research programme on selling to SMBs.

One solution is to make assumptions from size about behaviour.

Companies hypothesise that high-end SMBs with, say, 20 to 500 employees, will be running complex business processes and need to handle complex IT environments.  Research by VIA showed that buying behaviour differs between companies with an IT department and those without.

"Identify the drivers and you can deploy the right resources."

For Dent, the key is to drill down to the level where you can segregate SMBs by how they buy: "Identify the drivers and you can deploy the right resources. We helped a Baby Bell in the USA do this with dramatic results."

Suppliers also need to understand why SMBs switch suppliers, says Dent: "Research we carried out for HP indicated that reliability problems and poor support lead SMBs to switch."

Harry Mycock, distribution channels manager at IBM UK, agrees about the importance of profiling.

Mycock says the rules of good direct marketing still apply: "Before we start a campaign we seek to understand how a vertical market, such as wholesalers, behaves, what issues they face, and how our technology can provide specific solutions to their problems.  We then phone only a selected 400 out of the list of 4,000.  You need to do a lot of preparation before you commence such a programme."

As with any marketing, the media used has to reflect the nature of the product and audience.

Mycock says: "Dell can reach SMBs through mass mailings and through pull-outs in the Sunday supplements precisely because it has a simple, limited product range with mass appeal.