How a Cloud Phone System Is Organized — Signal Concepts
A cloud phone system is built from five objects: locations (physical addresses), extensions (people or roles), devices (the phones themselves), phone numbers (what the outside world dials), and routing (the rules that connect a caller to the right extension). Every task in the Signal admin portal creates or connects one of these five.
What is the difference between an extension and a phone number?
An extension is an internal identity — a 3–4 digit number that represents a person or a role (Front Desk, Exam Room 2). A phone number (DID) is a public 10-digit number that callers dial from outside. Phone numbers point at extensions, menus, or routing rules; extensions ring devices. One extension can answer calls from many phone numbers, and one phone number can reach many extensions.
What is a device, and why is it separate from an extension?
A device is a physical or software phone — a Polycom or Yealink desk phone identified by its MAC address, or the Signal mobile and web apps. Devices are separate from extensions so that one person can ring on up to ten devices at once (desk phone, laptop, mobile), and so a desk phone can be swapped without touching the person's settings.
How does a call reach a person?
- A caller dials your phone number.
- Signal looks up the number's destination — an extension, an auto attendant menu, or a route with business-hours logic.
- Routing selects an extension; the extension rings every registered device simultaneously for its configured ring duration (default: 25 seconds).
- Unanswered calls follow the fallback — typically the extension's voicemail box.
Why do locations matter?
Every extension and device belongs to a location — a verified street address. Locations determine where emergency services are dispatched when anyone dials 911 (E911). A phone without a correct location cannot safely place emergency calls, which is why Signal requires one before a device goes live.
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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.