Breathe Networks has announced it has taken over the V21 customer base of defunct internet service provider (ISP) Biscit.

These customers can migrate to another ISP if they prefer, but will also be offered the chance of staying on one of Breathe's broadband packages.

The winding up of Biscit is the first big test of Ofcom's new rules that force ISPs to provide migration authorisation codes (MACs) within five working days to consumers who want to switch provider.

Biscit Internet, which only acquired V21 in October last year, went into administration on 5 March 2007 after weeks of rumour and speculation on internet forums.

BT, which was one of Biscit's wholesale providers announced on Friday last week it would be assisting Biscit customers, whose underlying service was provided by a direct connection to BT Wholesale's network.

This comprised around 6,500 broadband customers, but still left around 1,500 V21 customers whose broadband service came from wholesaler EurISP's network. This company has continued to keep the services live, but told Computeractive it was not set up to deal with customer services.

Breathe was approached and has agreed with EurISP to provide these customers with a service or, if they prefer, a MAC.

Breathe chief executive Marcus East said the company would continue to provide a broadband service while it contacts V21 customers over the coming week. As the company doesn't have email addresses for many of these customers it will contact them by phone to explain their options.

"People on EuroISP's network should not have noticed any disruption to their service. We will continue to provide the service no matter what they decide to do until the end of March," he said.

"We hope to be able to generate MACs for people by the end of the week which should give people who want to change enough time to find another service provider."

Those V21 customers who want to take a Breathe package should see no disruption, East said, and would be billed for the new service from 1 April 2007.

Biscit customers on BT Wholesale's network can from today call a special helpline, 0800 169 9576, to obtain a MAC from BT Wholesale. This will enable them to move to a new broadband service provider of their choice.

The aim is to help minimise disruption and downtime to their broadband service. Details of the helpline will be available from a web page that Biscit customers will be re-directed to from next Monday.

Customers of Biscit's dial-up and telephone services probably face the most disruption and have been advised to look for an alternative supplier. They have been unable to make outgoing calls, with the exception of 999 calls, since Friday. However, incoming calls are still provided.