Following its recent announcement that ADSL will be available to virtually the whole country by summer 2004, BT has announced it will bring the more business-oriented broadband flavour, SDSL, to more places.

The SDSL upgrade is happening in the next few months - but don’t expect a demand-tracker like the one BT used for ADSL rollout. Instead, the telco is going to ask other ISPs which areas should be favoured, and it wants their opinions by next Friday, 14 May. BT plans to double its SDSL coverage by upgrading another 150 exchanges.

The symmetric DSL standard is ideal for businesses that host servers and pump traffic onto the Net since it offers up to 2 Mbit/s both ways on a phone line, while ADSL typically offers 256 Kbit/s or less.

“Rather than a public registration period, we have asked service providers to tell us where there is a demand,” said a BT spokesman. “That is a more appropriate mechanism for a service that is more niche than ADSL.” BT currently offers SDSL in London, as well as Birmingham, Manchester and parts of urban Scotland. The next exchanges are likely to be in similar areas.

BT’s SDSL has several differences over ADSL: it needs exclusive use of the phone line, and costs substantially more (£170 to £345 per month for 512 Kbit/s to 2 Mbit/s). It is also offered at a better contention rate - fewer users share the line upstream of the exchange. It stops short of competing directly with the telco’s more expensive leased line services, however, which are uncontended - the customer has exclusive use of bandwidth.

The move was welcomed by Bulldog, which offers a service based on BT’s SDSL, as well as having its own SDSL equipment from 38 telephone exchanges in London. More BT-enabled SDSL exchanges will allow more competition, said David Ferguson, Bulldog’s chief commercial officer.

“As our service is based on BT’s Datastream [a more flexible offering then the usual Ipstream package], we can offer better contention ratios,” he said. Bulldog even offers an “IP leased line” service with no contention, and plans to offer this at the newly enabled exchanges.