BT is offering a reward of £15,000 to anyone with information on a burglary at an exchange in Stepney, East London that took down phone and internet communications for homes and businesses.
The thieves are also being linked to other similar burglaries in the capital.
Raiders hit the Stepney Green exchange on Commercial Road before dawn on September 25. The bagged nine 21CN network cards costing thousands of pounds each.
The burglary is being investigated by Tower Hamlets CID.
Detective Sergeant Rob Brown said: "This type of incident can cause real disruption to the telephone network and deprive people of the use of their telephones and computers. It is essential the persons responsible for this irresponsible crime are brought to justice and prevented from committing similar acts in the future."
"BT takes these matters very seriously and we fully support the Met Police in their enquiries," BT security director Mark Hughes said. "We have decided to offer a reward for information to bring those people responsible for this, and similar incidents in the London area, to justice."
The Stepney Green burglars struck two weeks after thieves hit another London exchange in Mayfair. Gear reported to be worth millions was swiped while police and photographers thronged outside the pub next door, where Guy Ritchie was throwing a party to celebrate the release of his new film.
A BT spokesman said that incident is also still being investigated. ®