Some businesses across the UK could be left without an internet connection within the next couple of months as BT charges ahead with its plans to turn off older network services.

Around 10 percent of businesses in the UK are still using BT's ADSL and SDSL services that are due to be switched off in June, according to internet service provider Timico. 

The provider is warning businesses that a nationwide switch-off of the BT 20CN broadband network could leave those who have not made the switchover without internet connectivity.

20CN is BT’s first generation, old broadband network which provides standard copper broadband service of speeds up to 8Mbps.

This has been superseded by the 21st Century Next Generation Network (21CN), which is now available to around 92 percent of UK homes and businesses.

As part of the roll-out of superfast broadband, BT is closing some of its older ADSL and SDSL broadband products. In locations where up to 16Mbps ADSL broadband or up to 76Mbps FTTC (fibre-to-the-cabinet) broadband is now available, BT will be withdrawing its older products by in June.

Tony Tugulu, director of Managed Networks at Timico, said: “This switch-off will have catastrophic consequences for businesses who are unprepared for the migration to 21CN.

“As an example, one Timico customer  in the retail sector with several hundred sites across the UK had, until very recently, almost 20 percent of its sites connected to old services. If left unchecked this would have meant price rises and then loss of service to dozens of business locations, thousands of pounds in fee increases and severe business disruption.”

The retirement programme began in October 2013 and at a rate of up to 400 exchanges retired each month, the operation has moved quickly. In total, 2549 exchanges are expected to be shut down.

“We are using this opportunity to alert businesses to this issue and urge everyone to check that they are using up-to-date broadband technology," added Tugulu. "In a worst case scenario businesses could see their services cut off completely, leaving them with no internet connection and the potential for expensive reconnection charges."

Steve Broadhead, founder of Broadband-Testing Labs, said: "Obviously all services eventually come to end and we are in the copper to fibre switchover era at the moment."

However, Broadhead added that service providers need to take it upon themselves to inform their customers on what is happening and suggest suitable alternatives. "Where a company has dozens or hundreds of branch offices to upgrade, even if this is part of the service provider offering, it does take months to migrate, so they need to be doing this right now," he said. 

A BT spokesperson said: "Most communications providers have already completed or are nearing the end of migrating their customers across to the next generation network. That network currently reaches 92 per cent of UK premises whilst the remainder of premises will be unaffected as legacy broadband services will be maintained in these areas.

“We are working closely with industry to ensure the smooth migration of any remaining end customers onto our next generation network. There is still plenty of time for end customers to migrate as we will continue to maintain the legacy broadband network until the end of September 2014. We would urge communications providers to migrate their customers onto the next generation network by the end of June 2014 however, and to contact us should they experience any problems.”

BT turned off its dial-up service last September, leaving a number of customers in rural locations without an internet connection.