Telappliant
    For Existing PBX Systems

    SIP Trunking

    Keep your current phone system and connect it to the digital network. Replace your ISDN lines without replacing your PBX.

    SIP Trunking connecting PBX to cloud network

    What is SIP Trunking?

    SIP (Session Initiation Protocol) Trunking is a method of connecting your existing phone system (PBX) to the telephone network over the internet, replacing traditional ISDN lines. It allows you to keep your current phone hardware while transitioning to digital connectivity.

    Why Choose SIP Trunking?

    The smart way to transition if you have an existing phone system

    Keep Your PBX

    Continue using your existing phone system hardware and investment.

    Simple Connection

    We connect your PBX to our digital network, replacing ISDN lines.

    Business Continuity

    Built-in failover and redundancy to keep your phones working.

    Cost Savings

    Typically lower call costs than traditional ISDN services.

    Key Benefits

    • Protect your existing PBX investment
    • No need to retrain staff on new systems
    • Keep your current phone numbers
    • Scale up or down channels as needed
    • Lower per-channel costs than ISDN
    • Future-proof connection to digital networks

    Ideal For

    • Businesses with a working on-premise PBX
    • Organisations with significant PBX investment
    • Companies not ready for full cloud migration
    • Businesses needing gradual transition

    Ready to Replace Your PBX?

    If your PBX is aging or you want a fully managed solution, consider Cloud Communications.

    How SIP Trunking Works

    A straightforward transition from ISDN

    1

    Compatibility Check

    We verify your PBX supports SIP and assess your broadband requirements.

    2

    Port Your Numbers

    We transfer your existing phone numbers to SIP trunks seamlessly.

    3

    Configure Connection

    We set up the SIP trunk connection to your PBX with the required channels.

    4

    Go Live

    Your calls route over SIP – often with improved quality and lower costs.

    Related Solutions

    Explore other options for your business

    Teams Voice

    Already using Microsoft 365? Add calling to Teams for unified comms.

    Cloud Communications

    Replace your PBX entirely with a fully managed cloud phone system.

    Ready to prepare for 2027?

    Take our free readiness check to find out what you need to do before the PSTN switch-off.