Numbers
Existing business numbers can often be ported, but ranges and lead times should be checked before the cutover date is fixed.
PSTN vs VoIP / SME guide
PSTN vs VoIP: what actually changes for your business?
Moving from the legacy phone network to IP voice is not just a handset swap. The useful migration plan covers numbers, call routing, connectivity, analogue devices and what happens if the internet connection fails.
The practical difference
Old line versus modern phone system.
PSTN is the legacy public switched telephone network. VoIP carries calls over IP connectivity and usually sits inside a broader business phone system with routing, apps, reporting and central administration.
Devices
A modern setup can combine Yealink desk phones with Linkus desktop/mobile softphones rather than giving every user the same endpoint.
Call flow
Queues, auto attendants, opening hours, overflow and reporting can be redesigned as part of the move instead of copying old limitations.
Dependencies
Alarms, lifts, door entry, fax and other analogue equipment need separate attention because not every PSTN-connected device can move directly to VoIP.
Migration sequence
Move the service, not the risk.
01
Audit the estate
List numbers, lines, contracts, users, devices and analogue dependencies.
02
Design the replacement
Choose the Yeastar deployment, Yealink/softphone mix, SIP connectivity, call flow and resilience.
03
Build and test
Configure users and routing before the number-porting cutover.
04
Port and verify
Move numbers in a controlled window and validate inbound, outbound and fallback behaviour.
What changes operationally
VoIP moves responsibility from the phone line to the wider network.
With a traditional PSTN line, voice and local power behaviour were closely tied to the telephone network. A modern VoIP system depends on IP connectivity, local network equipment and power at the site. That gives businesses much more flexibility, but it also means resilience has to be designed rather than assumed.
Internet and LAN quality matter
The office internet connection is only one part of the voice path. Switches, Wi-Fi, routers, QoS configuration and remote-user networks can all affect call quality. A migration should therefore check the network used by the people making calls, not just the headline broadband speed.
Power resilience becomes part of the design
If a site needs calling during a local power failure, the router, switches, PBX appliance where applicable and endpoints may need UPS protection or an alternative route. Mobile failover and rerouting can also form part of the business-continuity plan.
Number ownership still matters
Moving to VoIP does not mean changing the number customers already know. Existing numbers can often be ported, but the current provider, account data and number range should be validated before the final migration date is committed.
PSTN vs VoIP comparison
The practical differences for an SME.
VoIP adds flexibility, but the strongest migration replaces legacy limitations with a planned phone system rather than simply moving the same call flow onto IP.
Calls are no longer tied to one socket
Users can work from Yealink phones, Linkus clients or supported integrations while presenting the same business identity.
Changes become software-driven
Extensions, opening hours, call groups and routing can be managed centrally instead of depending on fixed legacy lines and hardware wiring.
Failure routes can be designed
Alternative destinations, connectivity resilience and mobile routing can keep customer calls moving when a site or connection has a problem.
Non-voice devices need separate treatment
Lift phones, alarms, fax, intercoms and other legacy services should be checked with the relevant equipment provider rather than assumed to behave like a normal voice extension.
PSTN migration
Tell us what is still connected.
We can help turn the current estate into a practical migration plan and a bespoke quotation.