0121 214 1100
0344 257 8222

Switching to SIP

ISDN Switch Over


BT Openreach have announced their intention to cease the PSTN (Analogue line) and ISDN network. Openreach are starting with a cease in new supply in 2020 and a full migration to newer technologies by 2025. This announcement is going to affect many businesses in the near future, especially those wishing to increase their existing ISDN channel capacity or those looking to upgrade their current business telephone system.

With over 30 years serving the UK’s SMEs Midland Telecom is a specialist in ISDN to SIP conversions, and offers bespoke solutions tailored to your business. Whether it’s an upgrade to your existing system using your current handsets or a no physical handset telephony solution we’re here to help.

This guide will help you understand your new service and basic troubleshooting which can carried should you have any issues.

Basics of SIP


SIP is now widely used among many different businesses, unlike traditional ISDN or PSTN lines, SIP relies on a steady broadband connection rather than physical lines into your premises. All your telephone numbers can run from the broadband connection.

We would advise having a separate broadband connection for your SIP and local network as sharing the connection can cause general issues with calls such as cutting out, one-way speech or noise on the line. There are some exceptions to this, if you are running on a faster broadband connection such as an 80/20 FTTC or Leased line then you will be able to share the connection as there will be a sufficient amount of bandwidth for both voice and data use.

What to expect when switching over


On the day of your switchover, one of our engineers will attend site to configure the phone system and to ensure that your new SIP service is working correctly. You may notice that your old lines will be inactive as they will be ported to the new SIP service, porting can be completed on the day of the switchover or can be done after the install. Porting numbers afterwards can allow us some time to test the service to ensure the broadband connection and SIP trunks are working as expected.



If you find that you cannot make or receive any calls on your telephone, please check the broadband connection as a first step. To do this you will need to check if there is a DSL light or internet light lit on the router. This light should always be solid green, if you see that it is flashing or off then this may mean the connection itself is down. In some events, the session may be stale, and the DSL will show as solid green. In all these scenarios we recommend rebooting the router on site.


Majority of the Assured broadband connections that we supply will use a Billion router. This router will have a square button on the back which will allow you to reboot the router.


Not all SIP connections will be using a Billion router, it may be that you have a Draytek or a router supplied by your own IT. We would recommend the same steps, however if equipment is maintained by your IT then please contact them first as they may advise differently.

If the issue persists then the next step would be to contact our support team so we may help you resolve the issue.

For further information on troubleshooting SIP issues please see our SIP support page here.

Get in touch

Please enter your email, so we can follow up with you.