Support Center / Switching to Signal
Replacing an On-Premises PBX with a Cloud Phone System
Retiring an on-premises PBX (Avaya, Nortel, Panasonic, NEC, Asterisk) for a cloud system trades a server room and PRI circuits for provisioned phones and an internet connection. The concepts map cleanly; the projects that go sideways skip network prep or forget the analog stragglers — fax lines, door buzzers, alarm dialers.
Concept mapping
On-prem PBX world | Cloud equivalent |
|---|---|
PBX chassis + license | Nothing to own — the platform is the service |
PRI / analog trunks | SIP connectivity (included) |
Digital/proprietary handsets | Standard SIP phones (replace) |
Hunt groups / pickup groups | Call groups + BLF pickup |
AA / voicemail cards | Auto attendants + voicemail (included) |
Punch-down cross-connects |
Proprietary digital handsets (the majority of legacy PBX estates) do not convert — hardware replacement is part of the budget, offset by the maintenance contract you're ending.
The analog inventory (do this first)
Walk the building and list everything with a phone cord that isn't a desk phone: fax machines, door entry, elevators, alarm panels, franking machines, cordless bases. Each needs a decision — an ATA, a dedicated cellular device (alarm and elevator lines have code requirements; involve your alarm vendor), or retirement. This list, not the desk phones, is where PBX migrations slip.
Network first, then phones
Your LAN carried signaling to the PBX; now it carries the calls. Before hardware arrives, work through network readiness: PoE budget, QoS, SIP ALG off, bandwidth. A clean network makes cloud voice boring — the goal.
Sequence and risks
Standard go-live discipline applies, with two PBX-specific risks: port every number (old PBXs hide DIDs in unused DID blocks — pull the full inventory from carrier bills, not PBX programming), and keep the PRI until the port completes — disconnect order matters, and carriers won't resurrect a lost block quickly.
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Last reviewed August 6, 2026. Still stuck? Contact Signal Support from your portal — include what you expected, what happened instead, and one example phone number or extension.