VoIP vs PBX (and the difference)
VoIP and PBX are often used interchangeably but mean different things. VoIP is the transport layer (calls over IP). PBX is the application layer (call control, extensions, IVR, recording). Most modern systems combine both, but they are distinct concepts.
Side-by-side
| VoIP | PBX | |
|---|---|---|
| What it is | Protocol layer (SIP+RTP) that carries voice over IP networks | Application that routes/controls calls inside an organization |
| Examples | SIP, H.323, WebRTC | Asterisk/FreePBX, 3CX, RingCentral, Teams Phone |
| Layer | Transport / signaling | Application / business logic |
Possible combinations
- VoIP without PBX: a softphone or AI voice agent calling a SIP trunk directly — no internal extensions or IVR.
- PBX without VoIP: a 1990s analog PBX with copper-wire trunks — legacy, mostly extinct.
- VoIP + PBX (most common today): an IP-PBX (FreePBX, 3CX, Teams) speaking SIP to upstream carriers and to internal endpoints.
In short
If someone asks 'should I get VoIP or a PBX?' the answer is usually 'both' — you want a modern IP-PBX (or hosted/cloud PBX) connected via VoIP (SIP trunks) to a carrier like DIDHub.
Related terms
Related glossary terms
Asterisk (open-source PBX framework)
Asterisk is the original open-source telephony framework, started by Mark Spencer in 1999. It is a Class 5 PBX engine: it terminates SIP/IAX
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Attestation levels are the three trust ratings that an originating carrier assigns to outbound calls under STIR/SHAKEN. They tell the termin
Auto-Provisioning (zero-touch desk phone setup)
Auto-provisioning is how you deploy 50, 500, or 50,000 desk phones without manually configuring each one. The phone boots, fetches its confi
BYOC (Bring Your Own Carrier)
BYOC is a deployment model where you use a third-party SaaS platform (Vapi, Retell, Microsoft Teams, Zoom Phone, Twilio Flex) for the call-c
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