Although 56Kbps (kilo bits per second) modems have been on the market since 1997, the wrangling continues over who deserves the credit and royalties for the technology.

This week US company Analog Devices, which makes modem chipsets, settled out of court for an undisclosed amount with Brent Townshend — the man who holds five patents on the 56K modem technology.

This is the latest round of a battle that has gone on since 1997 when Townshend announced that he had found a way to boost download speed by 66 percent over the performance of the fastest modems. Many companies licensed the technology but others didn't. Modem chip maker Rockwell fought Townshend in court for three years to avoid paying, but finally settled out of court in 2001 for an undisclosed amount.

Other Townshend suits continue against chip manufacturers Agere Systems, ESS Technology, Intel and network equipment maker Cisco Systems. Townshend says that these companies have used his technology without permission and they counter that he unreasonably asks for too much. A single trial for all the companies is set for July 2004.

An Agere spokeswoman says Townshend's suit has no merit and that Agere believes it does not need a licence. A Cisco spokeswoman says it won't comment on ongoing litigation. ESS and Intel could not be reached for comment.

Theoretically the suits could have an impact on bank accounts of corporations because by law, Townshend could sue users with unlicensed modems. Experts say that scenario is unlikely because there would be so many grievances and each user would ultimately have to pay very small amounts. Plus Townshend says he is not looking to individual companies for recompense.

But he does note that the law also prohibits the sale of unlicensed items, so supply channels for unlicensed modems could be shut down. Townshend says he is focused on those that make the modems.

With virtually all commercial PCs shipping with 56K modems as a standard feature, the number sold this year is expected to reach about 120 million worldwide, says Ernie Rapiere, a senior analyst with Mobility IT. Townshend won't say how much this has meant, but if all the modems sold this year were soft modems, they would represent $26.4m (£15m) in licence fees. In 2002 vendors sold 98 million modems.

Townshend's patented discoveries enable downloading data from the internet at up to 56Kbps over a standard analog dialup phone line. That speed is achievable only in the download direction because it involves no noisy analog-to-digital conversions on the line that decrease data rates. Digital-to-analog conversions create less noise, and that is the only type of conversion necessary from an ISP using digital modems at its points of presence. Upload speed for the modems is 38.6Kbps.