Did You Know? BT have announced their plans to migrate many customers to an IP based network by 2025, eventually switching off the ISDN network. As the leading business communications provider this change will improve communications between millions of businesses across the UK. As of August 2013, there were around 3.2 million active ISDN lines in the UK however by 2025 most organisations will have made the move to a hosted service. Because Corporate Telecom is an authorised partner with BT, we can provide BT Cloud Voice as your solution.