Transfer from ISDN to SIP or buy virtual numbers

SIP Trunks – Eliminate Your ISDN Line Rental Charges with TNBN
Over 80% of ISDN lines will have moved to SIP by 2019, and with BT Group aiming to move all ISDN customers to IP by 2025, it’s time for you to plan your move.

Buy virtual company telephone numbers

We supply UK & international telephone numbers for your business.

Click here to see the full package

Transfer from ISDN to SIP

“Our trained IT technicians are ready to help”

Click here to obtain your transfer pack

Buy SIP Trunks & Data Connections

We aim to save you up-to 40%

Click here to make an enquiry

  • TNBN SIP Trunks cost only £5 per SIP

    A savings of approximately 70% compared to ISDN channels.

  • Built in Fraud Detection

    By default, we turn on fraud detection for all services. providing a timely response and notification to fraud attempts.

  • High-call quality, delivered over high-speed Voice Approved circuits

    If you require Fibre, Leased lines or Ethernet First Mile (EFM) TNBN offers a number of connectivity solutions to suit any sized business.

  • Keep your existing phone number

    The TNBN porting system enables you to keep all your existing phone numbers when transferring from ISDN to SIP.

  • Flexible number display

    Decide which number you want to display on outbound calls. Great for contact centres. Use CLI flexibility to present a preferred telephone number rather than your own when making an outbound SIP call.

  • Add new phone numbers from any UK dialling code

    Our geographic range of telephone numbers can create an attractive image that you live or work any where in the UK. For example your business could advertise in Manchester with a local 0161 number but the inbound call will route to your preferred office or mobile based anywhere in the UK, offering a local based image for nationwide or expanding companies.

  • Manufacturer Approved

    Having more PBX manufacturer approvals than any other UK SIP provider has been an important foundation from the start. Our quality testing system provides customers with a stable and consistent solution.

  • FREE On going Support

    We are open Monday to Friday from 9am till 5pm (excluding bank holidays) offing dedicated support with voice & data engineers.

  • Business Continuity

    In the unlikely event you have a major fault we can route all calls to another office, landline or mobile ensuring business continuity

  • Moving offices

    Number flexibility with SIP trunking means that you can keep your existing numbers, even when moving out of the area, saving you costs on stationary whilst maintaining the perception that you still have a presence in the area you’ve moved from.

  • Add call recording to your SIPS

    There is a cost of 1p per minute for call recording which will give you 30 days cloud storage. Access our portal and download your recorded calls during the first 30 days or keep them stored on our servers at a cost of 1p per minute after your 30 days has expired.

  • Instant FREE provisioning

    Our products can be instantly provisioned through our portal. Add more SIP trunks as and when you require them within seconds.

  • Back up data centres

    Our data centres hosting your SIPS have multiple back up failover servers providing redundancy in the system design. The components in our systems are duplicated should anything go wrong proving a stable solution for your SIP trunks.