SIP Trunking is our preferred replacement for traditional ISDN. It connects your phone system to the PSTN via broadband, FTTC or Ethernet connectivity. Our SIP Trunks work seamlessly with each of the leading IP phone systems in the UK marketplace. Compared to ISDN our SIP trunking service is less costly per channel and more flexible in how and where geographic telephone numbers can be used. It’s also quicker to install and provision and, as standard, it delivers extremely robust business continuity.