How to switch carriers without dropping live calls

Switching carriers does not have to mean a risky midnight cutover. The safe pattern is to run both Carrier trunks in parallel, shift your outbound routing onto the new one gradually, let the old Trunk drain its in-flight calls, then deactivate it. At no point is there a window where calls have nowhere to go.

Add the new carrier alongside the old

Add the new carrier as a fresh entry under Admin then Carriers. Keep the existing carrier exactly where it is. VICIdial is happy to hold multiple Server trunk entries at once, each with its own account block and dial pattern. Stage the new one, confirm its SIP peer is reachable with sip show peers, and place a single test call before it carries any real traffic.

Shift routing gradually

Now move traffic over in stages instead of all at once. The cleanest lever is your campaign dial routing: point a few campaigns or a slice of your dial patterns at the new trunk, watch the answer rate and audio quality, then widen it. If you run Least-cost routing, adjust the route priority so the new carrier takes a growing share while the old one stays as fallback.

stateDiagram-v2
  [*] --> OldOnly
  OldOnly --> Both: add new carrier, route a slice
  Both --> Both: widen new, watch quality
  Both --> NewOnly: drain old, deactivate it
  NewOnly --> [*]

Through this window both trunks are live. New calls increasingly land on the new carrier, and anything already up on the old carrier keeps talking. That overlap is the whole point: it removes the cliff edge a hard swap would create.

• Old only: all traffic on the original carrier, new one staged and tested.
• Both: routing split, new carrier carrying a rising share, old one as fallback.
• New only: old trunk drained and deactivated, all traffic on the new carrier.

Drain the old trunk, then deactivate it

Once the new carrier carries the full load cleanly, stop sending new calls to the old trunk and let its existing calls finish naturally. Watch the active Channel count on the old carrier fall toward zero. When nothing is left on it, set its Active flag to N. Deactivating drops it out of the conf files on the next rebuild and leaves the entry in place in case you ever need to flip it back.

This parallel-run approach is the same discipline used across the VICIdial carrier integration guide, and it leans on the same multi-carrier setup described in running multiple carriers with failover.

On a VICIfast server you bring your own carriers, so swapping one out is entirely under your control. Your dialer provisions over HTTPS in under 40 seconds, and you can run both old and new trunks side by side for as long as the migration needs.