Twilio, Plivo, Telnyx, SIP: telephony plumbing explained
Agentric Team ·
Phone calls are more technical than they look — but as an Agentric customer you mostly don't need to care. Here's the plumbing in plain terms, for when you're curious or making choices.
The layers
Carriers — the networks that physically carry calls (BT, EE, Vodafone). You never deal with these directly for business VoIP.
CPaaS providers (Communications Platform as a Service) — Twilio, Plivo, Telnyx, Vonage et al. These sit between carriers and software: they hold numbers, receive calls, and expose them via APIs/webhooks. When your phone rings, a provider like this is what hands the call to software.
SIP — Session Initiation Protocol, the standard for voice calls over the internet. "SIP trunk" = a connection between a phone service and the internet-telephony world. When we say "SIP URI", we mean the internet address your provider forwards calls to.
Webhooks / TwiML — when a call arrives, the provider asks our server "what should I do?" via HTTP; our response (TwiML-style instructions) says "greet the caller, then connect them to the AI agent." Every step of the call is that request/response loop.
The two ways calls reach your AI
- Forwarding — your existing number redirects (when busy/unanswered/all calls) to the Agentric number. Simple, instant, uses your current provider's call-forward feature.
- Provisioned number — we hold a number on a CPaaS provider; calls arrive directly. Cleaner for a dedicated business line.
What this means for you
The plumbing decision that actually matters: keep your number or take a new one. Everything else is configuration we handle — webhooks, SIP, media streams, the agent bridge. The setup page gives you dial codes or SIP details; the complexity is our job.
The provider note
Different telephony providers have different coverage, price and reliability profiles. Agentric's voice layer is provider-agnostic (Twilio-compatible webhooks work with Plivo, Telnyx etc.) — if you have provider preference or an existing SIP trunk, it can plug in at the same seam.