Support Center / Device Library
Connecting Generic SIP Devices — Softphones, ATAs, Intercoms
Any standards-based SIP device can register to Signal using an extension's credentials: third-party softphones, analog telephone adapters (ATAs) for fax machines and cordless sets, door intercoms, and paging amplifiers. These devices aren't auto-provisioned — you enter three values manually.
The three values
From the extension's Softphone tab: SIP username, SIP password, and the server domain. In the device's SIP account settings, these map to username/auth name, password, and registrar/proxy. Use TLS transport and SRTP where the device supports them; port 5061 (TLS) or 5060 otherwise.
Device-type guidance
Device | Guidance |
|---|---|
Softphone apps | Prefer Signal's own apps; for third-party clients, one extension per user, TLS on |
ATA (fax) | Dedicated extension; disable voicemail on it; T.38 or G.711 pass-through per the ATA's fax settings |
ATA (cordless/analog) | Dedicated extension; confirm E911 location — analog handsets are exactly where mislocated 911 calls happen |
Door intercom / paging | Dedicated extension with external dialing disabled; internal-only whitelist where supported |
Rules that keep this safe
- One device, one extension. Shared credentials make fraud tracing and resets collective punishment.
- Least privilege: appliances get dialing permissions cut to what they do — an intercom never needs international calling.
- Inventory them: generic devices don't show model/MAC detail like provisioned phones; name their extensions descriptively ("Lobby Door Intercom") so audits stay sane.
- Fax over VoIP is workable but sensitive to packet loss; high-volume fax belongs on a dedicated e-fax service rather than an ATA.
Related articles
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.