SIP trunking can replace existing ISDN lines to connect phone systems to the public phone network over the internet. This reduces costs through lower line rental and call charges compared to ISDN. It also provides improved business continuity through backup connectivity and flexibility to dynamically pool staff resources across sites. InTechnology is recommended for SIP trunking due to their managed MPLS network designed for voice, experience supporting both new and old telephony systems, and reliability from carrier-grade platforms.

1. SIP Trunking: The end for ISDN? Phil Dyson Product Group Manager – Voice Services

7. How does it work? Public Telephone Network ISDN Data Internet VPN

8. How does it work? Public Telephone Network Data Internet VPN ISDN