Choosing telephony and SIP for AI voice agents
The carrier is the part of a voice agent nobody thinks about until calls drop or sound robotic. These are the questions worth asking before you port numbers.
Media streaming
Your agent needs raw call audio in real time, usually over WebSockets or SIP to your media server. Confirm the provider supports bidirectional streaming in the regions you need.
- Twilio — Programmable voice, SIP, and phone numbers widely used for AI phone agents.
- Telnyx — Global SIP trunking, numbers, and realtime communications for voice AI.
- SignalWire — Realtime communications platform with SIP, voice, and programmable relay APIs.
- Plivo — Cloud communications platform offering voice calling and SIP infrastructure.
Latency and network
Providers that own more of their network can shave round-trip time; place your media servers in the same region as the carrier edge you terminate on.
Numbers, coverage and compliance
Check number availability per country, local registration rules (for example business-identity requirements for US SMS and caller ID), and call recording consent rules where your callers are.
- Bandwidth — Enterprise communications platform providing numbers and voice APIs.
- Vonage — Communications APIs including voice and SIP for contact center and agent use cases.
SIP trunking vs. programmable voice
If you already have a PBX or contact centre, a SIP trunk into your agent infrastructure is often simplest. Greenfield projects tend to start with a programmable voice API, and many platforms bundle numbers for you.
- LiveKit — Open-source WebRTC SFU and cloud for realtime audio used by voice agents.
- Twilio — Programmable voice, SIP, and phone numbers widely used for AI phone agents.
- Telnyx — Global SIP trunking, numbers, and realtime communications for voice AI.
Comparisons
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- Voice Agent Platforms (12)
- Telephony & SIP (7)
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