TNBN is Britain’s leading Business Digital and IP Phone Company. We connect schools, hospitals, banks, shops, libraries, broadcasters, governments and businesses - large and small - to the world
Openreach have announced that they will be switching off the traditional singe analogue, analogue multiline, ISDN2 and ISDN30 channels during December 2025 with its replacement being FTTC Broadband and SIP Trunks should you wish to make and receive phone calls over VOIP. The UK is to switch to a single IP network connectable by SIP Trunks delivering faster, clearer and more cost effective communications for voice, data and video.
How will you connect? (see your options below)




Why is SIP the future replacement for Multi lines & ISDN and how will the change benefit you?
Lower costs – both rental and calls reduced by up-to 70%
Keep your existing phone numbers
99.99% Resiliency using fail over data centres
Re-route calls to mobiles and landlines in seconds
Scale lines up and down quickly
Set call spend perimeters for dial through fraud prevention
PAYG SIP Trunks only £7 each per month
Bundled SIP Trunks only £15 each per month

How will Sip trunks alter the way you make and receive calls compared to ISDN or Multi Lines?
Your current IDSN set-up
Handsets
Your phone system (PBX)
On-site IDSN box
Your office
Telephone exchange
Your future SIP set-up
Handsets
Your phone system (PBX)
On-site router
Your office
Data Centre