Switching phone provider without downtime

Run in parallel

Set the new system up on temporary numbers while the old one carries live calls. Staff install the app, learn the transfer buttons and set their voicemail with no pressure. Nothing customer-facing has changed yet.

Test the call flows

• Ring the main number from an outside mobile in and out of hours
• Check every direct dial reaches the right person
• Test transfers, hold and voicemail delivery
• Confirm what happens when nobody answers

Cut over and keep a net

Port on a quiet mid-week morning, keep the old lines live until the port completes, and have a divert to a mobile ready. Cease the old service only once you've taken real calls on the new one.