LiveKit vs. Twilio for Voice AI Agents: A Practitioner Comparison
These two get compared constantly because they solve overlapping problems from opposite directions. Twilio is a hosted telephony/communications API that added voice AI tooling (Media Streams, ConversationRelay) on top of a PSTN-first platform. LiveKit is a WebRTC infrastructure project — open source, self-hostable — that added an agents framework and SIP integration on top of a real-time-media-first platform. Which one is "better" depends entirely on which direction you're starting from.
Architecture: what you're actually renting or running
Twilio gives you a managed PSTN gateway, a Media Streams API that pipes call audio to your own STT/LLM/TTS pipeline (or their newer built-in AI stack), and a global carrier network you never have to think about. You write application logic; Twilio owns the infrastructure between the caller's phone and your server.
LiveKit gives you a WebRTC SFU (selective forwarding unit) you can self-host or use as a managed cloud, an open-source agents framework for building the STT/LLM/TTS pipeline as a "participant" in a room, and SIP trunk integration (via LiveKit SIP) to bridge that WebRTC world to real telephone calls. You're closer to the media layer, which is more control and more to operate.
Latency: it's not just "WebRTC is faster"
This gets stated as a blanket truth and it isn't one. For pure browser-to-browser or browser-to-agent audio, WebRTC's UDP-based transport genuinely has a latency edge over the codec/network path of a traditional PSTN call. But the moment either platform touches a real phone number, you're going through carrier infrastructure and a SIP trunk regardless — at that point the latency difference is dominated by your STT/LLM/TTS pipeline's processing time, not by which platform is moving the audio.
Where LiveKit's architecture has a real, consistent latency advantage: multi-participant or agent-to-agent scenarios, and cases where you control both ends of a WebRTC session (a web-based voice assistant, for instance) and never touch PSTN at all.
Control vs. operational burden
This is the tradeoff that actually decides most builds. Self-hosting LiveKit gives you control over the media path, custom codec handling, and no per-minute platform markup beyond your own infrastructure cost — but you're now operating a real-time media server, which means you own scaling, monitoring, and the failure modes that come with running your own SFU under load.
Twilio's model inverts this: you give up that low-level control in exchange for not operating telephony infrastructure at all. For a team without dedicated infra capacity, this isn't a minor convenience — it's the difference between shipping in weeks vs. months.
The gotcha nobody mentions until it bites: NAT and firewall reality
If your voice agent is browser-based and your caller is inside a corporate network with a restrictive firewall — which describes a large share of enterprise users — WebRTC's UDP-first connection negotiation can fail silently unless you have TURN relay infrastructure correctly configured. This is a LiveKit-specific operational cost (TURN servers, correct ICE configuration) that doesn't show up in a feature comparison and absolutely shows up in support tickets after launch. Twilio's PSTN-first model sidesteps this entirely for phone-based agents, since there's no WebRTC negotiation between caller and platform.
When each one wins
Pick Twilio when your primary channel is real phone numbers, you don't have infrastructure capacity to run media servers, or you need to move fast on a phone-first deployment with a small team.
Pick LiveKit when you need a browser-based or multi-modal agent experience (video, screen share, multi-participant), when per-minute cost at scale matters enough to justify self-hosting, or when you need low-level control over the media pipeline that a managed platform won't expose.
Pick neither, or both when the real answer is a hybrid: LiveKit for the agent/media layer, bridged to PSTN via SIP trunking through a carrier or platform like Twilio's trunk product for the phone leg. This is more common in serious deployments than the "vs." framing suggests — see our architecture walkthrough for building a LiveKit voice agent for how that bridge actually gets wired.
If you're scoping a build and the Twilio-vs-LiveKit decision is blocking you, that's usually a sign the actual requirements (channel mix, scale, team capacity) haven't been pinned down yet — talk to us and we'll help you get to the actual decision criteria.