Keep the phone to your ear and try not to worry about BT's crawling ants

The telephone network could soon be crawling with ants - and that is no bad thing, scientists at British Telecom say. These are "software ants", tiny programs whose sole purpose in their cyberlife is to route your phone call. Charles Arthur, Science Editor, investigates.

The next time you hear a brief silence on the phone line, it might have been caused caused by an ant - not a live one in the exchange, but a piece of software deployed by British Telecom to make its network function better.

After five years' work, researchers have developed tiny packets of self- contained code that can unblock "traffic jams" on computerised exchanges.

The idea came to scientists when they realised that ants in search of food behave in the way that, ideally, human software engineers would do when solving network problems.

Generally, an ant looking for food wanders at random. If it finds some it leaves a scent trail, and heads back to its nest. If another ant comes across the trail it follows it to the food and then also heads back to the nest.

However the trail dies away over time, so a small source of food will not attract much attention, whereas a promising store such as a bowl of sugar will, because more ants are attracted and their scent trails are continually reinforced.

In BT's ant world, the food is represented by computerised exchanges which are heavily loaded, and the ants by tiny programs, just 100 lines of "C" language, said Professor Chris Winters, head of the future systems group at BT's Martlesham Laboratories. When the programs find an overloaded exchange, they rewrite its "routing" list, diverting incoming calls. Tests show the "software ants" can perform the process in between 2 and 900 milliseconds - only just long enough to notice during a conversation. "If somebody cuts the cable connecting two exchanges but people are still on the line, the ants can reroute the call before it is lost," Professor Winter said.

The "ants" then leave a timestamp on the exchange to say when they rewrote the table. That performs the same function as the scent trail: if an arriving "ant" finds that the exchange is heavily loaded and the rerouting table has recently been rewritten, it will try to help out.

But the idea has not been easily accepted. "There are a lot of human issues," Professor Winter said. "If you tell the network manager not to bother with his central control of the network, because you've got a lot of ants that will run around and fix it for him, it causes some nervousness. It will take some time before it's accepted."

Other animal models being investigated include locusts, which can change their behaviour when a particular gas permeates their brain, and other insects. "If you want to understand something then it helps to look at fairly simple examples," Professor Winter said. "The human brain has perhaps 100 billion billion neurons. Ants have a handful - yet an ant colony can be unbelievably clever. We're learning from the millions of years that it has taken ants to evolve."

Four ants preserved in amber 92 million years old have been found in New Jersey in the US. They are 50 million years older than any found before.