The short answer
Evaluate POTS-in-a-box vendors on five things: analog fidelity for alarm and fax traffic, battery-backed hardware, per-line supervision with real alerting, multi-carrier failover, and documentation you can hand to an inspector. Price differences between vendors are small; failure behavior differences are not.
Hardware
- How many analog ports, and what happens when you exceed them?
- Battery runtime at full load, and is the battery user-replaceable?
- Is failed hardware replaced as part of the monthly fee?
- Can external antennas be added for weak-signal sites?
Transport and resilience
- Single-carrier or multi-carrier SIM?
- Does it fail over automatically, and how fast?
- Can fiber or broadband be primary with cellular as backup?
- Is traffic carried on a private APN or the open internet?
Supervision and alerting
- Is each analog line supervised, or only the device?
- Who receives alerts, and through what channel?
- Is alert history retained, and for how long?
- Is there a portal showing current state per line?
Signaling compatibility
- Which alarm formats have been tested with your central station?
- Has fax been tested at your typical page counts?
- Are elevator auto-dialers explicitly supported?
- Will the vendor run a paid or free pilot before commitment?
Commercial terms
- Is pricing per line, per device, or per site?
- What is included in install, and what triggers extra charges?
- Who owns the ported numbers if you leave?
- What is the exit process and notice period?
Last updated 2026-08-20.