The UK is moving away from the traditional analogue public switched telephone network and toward digital voice services. The public number can often be kept, but equipment connected to the line may need separate checks.
List phones, alarms, lift phones, payment terminals, fax machines, and door-entry systems before changing a line. Ask each supplier whether the device supports the proposed digital service and arrange a test after the change.
A virtual number can separate your public business number from a physical socket. Calls can route to a mobile, office line, or SIP phone while you replace equipment or move premises.
See virtual phone numbers, explore SIP, or ask for migration help.