Leading law firm migrates from ISDN to SIP

Alice Gosine

Alice Gosine

Goughs Solicitors are one of Wiltshire’s leading law firms that provide legal services for individuals and businesses, with seven offices across the country. In this blog we’re going to outline how we moved them from ISDN to SIP.

Goughs has been working with their IT provider over the last year to virtualise their VMware servers, moving to the cloud for greater resistance and reliability. 

The next phase, managed by Blackstar Solutions, was to virtualise the Mitel telephony system, migrate it to VMware, move away from traditional ISDN, and migrate all seven offices over to centralised SIP, with the purpose of rationalising lines and for cost-saving benefits. 

The solution and benefits

Blackstar offered the solutions of Virtualisation and migration of an on-premise Mitel MiVoice Connect PBX to a private cloud and migration of ISDN at all of Gough’s locations to centralised SIP. The benefits include:

  • Rationalised and centralised lines
  • No hardware or equipment on site
  • Cost savings on calls and line rentals 
  • Improved efficiency and security
  • High availability for maximum resilience


The solution

Goughs have had a Mitel MiVoice Connect telephony solution for seven years, with hardware and ISDN lines hardwired into each office. Goughs selected Blackstar Solutions (Blackstar) to support the Mitel system, pre-Covid because their incumbent provider did not have Blackstar’s skills or knowledge around the Mitel technology.

Goughs deployed Blackstar’s services to help them migrate their telephony over to SIP. Blackstar has repurposed the MiVoice Connect, which has been virtualised in VMWare in the customer’s data centre. The central server was a physical on-premise device, and now Goughs can reap the benefits of a private cloud solution, primarily for continuity, security and reliability.

The transition

Blackstar’s role was to virtualise the telephony estate away from physical appliances and move Gough’s telephony infrastructure to the data centre.

Blackstar conducted the migration in a phased approach, undertaking every element in a controlled manner. They decommissioned and unplugged the on-premise equipment, so Goughs no longer had cabinets full of equipment.

The next phase was to prepare the sites for porting the legacy ISDN DDI ranges to the new SIP service on a site-by-site basis. 

The final step was to migrate the users over to SIP, one office at a time, and then decommission the legacy equipment. 

Great agility and flexibility

Blackstar successfully migrated Goughs from legacy on-premise equipment to private cloud. The SIP trunking means they now benefit from inclusive local, national, and mobile calls, which has substantially brought their phone bill down.

The phased deployment enabled Goughs to report to the business as each phase was successfully completed, with a risk-free, seamless cutover and minimal downtime.

Positive feedback 

Gary Denham, IT Manager at Goughs Solicitors, commented,

“Everything was spot on, which is a rarity with suppliers these days! I have dealt with a lot of IT providers in my time and Blackstar excelled. I rarely gush about suppliers, but Blackstar has stood out as a shining light.

It was technically quite a complex project, but it was also the smoothest IT project I’ve ever seen – they made it appear seamless. The telephony is all now working exactly as it should and we are no longer firefighting our IT, all thanks to Blackstar.”

Ongoing support

Goughs originally planned to deploy Blackstar’s support services on a temporary basis for the SIP migration. Once the telephony system was virtualised, Goughs intended to retain all of their IT services with one central supplier for both voice and data. However, they were so happy with Blackstar’s service that they have decided to continue using them for their expertise.

Future plans 

Having moved away from ISDN to SIP trunking, Gough now have the infrastructure in place and the agility to switch to MS Teams using Direct routing in the future if they so wish. They would no doubt rely on Blackstar for their carrier routing and all other telephony support. 

Does your law firm use ISDN?

As you may have heard BT are switching off ISDN lines at the end of 2025. IN some places like Salisbury they have already switched it off. This doesn’t leave a lot of time to make the change. Law firms that leave making the move from ISDN to SIP to the last moment are going to bitterly disappointed. Their phone lines or internet may not work, leaving them without business-critical communication. If you’re a law firm and are using ISDN we want to help you make the transition to SIP or other cloud based options. 

What is your timeline to switch from ISDN to SIP?

We’re not here to scare you into making a rash decision, we’re consultants and act accordingly. We would love to know your timeline for making the change so we can help you migrate from ISDN to SIP if you are keeping your phone system. If you are looking to replace your phone system we can discuss your VoIP/Cloud options

As demonstrated with Goughs Solicitors we worked with them to make the transition from ISDN to SIP seamless. We took the time to understand their requirements and deliver on their timelines for making the switch. 

If you want to discuss your timeline for making the move away from ISDN, enter your details in the form below.  

Get in touch

Are you a law firm considering moving from ISDN to SIP or other cloud options? Fill out our details and we’ll contact you to discuss your requirements.