Phone What it triggers The software Fax What a fax costs Verified fax lines

What your architecture triggers

Not a boolean. Describe what you are building and the answer names a tier and its obligations, because "do we need a licence" has three different right answers.

The three tiers

App-to-app only (no PSTN)

Not interconnected

Members call members inside the app. No phone numbers, no calls to or from ordinary phones. Not interconnected VoIP, so none of the carrier obligations attach. ⭐ Build this first.

Numbers resold from a licensed carrier

Interconnected — burden on the carrier

Real numbers, real calls, and the carrier carries the registrations and the E911 plumbing. Costs margin. This is how nearly every small phone app actually ships. ⚠️ Read the carrier agreement for what it does NOT cover.

carrier holds E911, 499-A, USF, CALEA, CPNI

Own interconnected VoIP service

Interconnected — burden on the us

⚠️ E911 is the obligation that ends projects. Do not choose this tier to save money — it does not.

E911 with registered location
FCC registration + Form 499-A
USF contributions
CALEA lawful intercept
CPNI rules + annual certification
state registration and 911 fee remittance in some states

Engineering and regulatory orientation, not legal advice. The FCC obligations named here are real and enforced; confirm your own position with counsel before carrying a single call to a phone number.