If your voice AI never hears the call, none of the model work matters.
Enterprise telephony still has to answer on real trunks, keep the audio alive, and only then let speech and language tools join in. That bridge is what people mean by a voice AI gateway: the layer that connects your contact center, SBC, or call-control stack to the assistant you actually want on the line.
So this piece looks at 3 ways teams build that bridge today: Telnyx, AudioCodes VoiceAI Connect, and Bandwidth. Each one comes from a different heritage, and the fit depends on how your calls already move.
TL;DR: Best For
- Telnyx: Best for a licensed carrier with Call Control and built-in AI assistants on one owned stack.
- AudioCodes VoiceAI Connect: Best for connecting any contact-center or SIP trunk to any bot platform.
- Bandwidth: Best for global SIP trunking with Programmable Voice media streams and clean human handoff.
Bridging Enterprise Calls Into Voice AI
Before you compare vendors, it helps to share one frame. Enterprise voice AI still needs a telephony path, whether that is SIP, call control, an SBC, or programmable voice.
- Answer or route the call so the session starts on your trunks or call-control stack.
- Stream or adapt the audio so speech and models can hear and speak on the same live call.
- Run speech-to-text, a language model, text-to-speech, or a real-time model on that path.
- Transfer to a human when the conversation needs a person.
The sections below walk each vendor through that same bridge so you can see how the path looks in practice.
Enterprise Telephony: Best 3 Voice AI Gateway Picks Reviewed
|
Capability |
Telnyx |
AudioCodes VoiceAI Connect |
Bandwidth |
|
Telephony foundation |
Licensed-carrier Voice API with Call Control |
SBC heritage connecting trunks and contact centers |
Global SIP trunking plus Programmable Voice with BXML |
|
How calls reach Voice AI |
AI Assistant on the call, Gather using AI, or bidirectional media streaming over WebSocket |
Connector into Azure, Lex, Google, or a custom Bot API (HTTP or WebSocket) |
StartStream media over WebSocket (uni or bi), plus official OpenAI Realtime WebSocket and SIP paths |
|
Speech/bot flexibility |
Multi-engine STT and TTS; portal builders alongside custom agents |
Configurable STT and TTS providers; Self-Service Live Hub or Enterprise editions |
Programmable Voice features such as TTS, IVR, and recording alongside the stream |
|
Human handoff |
Mid-call control on the same carrier path |
Escalation-style contact-center patterns via the connector |
Transfer and SIP REFER into a live agent |
Telnyx
Telnyx is a licensed carrier with a Voice API built around Call Control, so answering, routing, and mid-call decisions live next to the AI features rather than in a separate gateway product.
On Telnyx, the bridge starts with Call Control. You answer or route on the carrier side, attach an AI Assistant at the start or mid-call, or stream media bidirectionally over WebSocket into your own agent stack.
Additionally, Gather using AI covers structured collection without inventing a side channel, and the Agent Platform runs on Telnyx’s owned stack so call control and assistants stay in one operational picture.
Key Capabilities
- Licensed carrier Voice API with Call Control for answer, route, and mid-call logic.
- AI Assistant that can join at answer or later in the session.
- Gather using AI for structured speech collection during the call.
- Bidirectional RTP media streaming over WebSocket into your own agents.
- Agent Platform on Telnyx’s owned stack, configured through Mission Control and the AI Assistant Builder portal.
- Multi-engine STT and TTS, plus WebRTC SDKs for client-side voice paths.
Why Teams Pick It
Teams pick Telnyx when they want carrier call control and AI assistants on the same owned stack, without a separate gateway product.
AudioCodes: VoiceAI Connect
AudioCodes VoiceAI Connect is built to connect any contact center or SIP trunk to any bot. It comes from SBC technology heritage, so the gateway mindset is natural: normalize the telephony edge, then hand audio and events to the bot platform you already chose.
With VoiceAI Connect, the bridge is the connector itself. SIP trunks or contact-center legs land on the AudioCodes edge, then VoiceAI Connect routes into Azure, Lex, Google, or a custom Bot API over HTTP or WebSocket.
You keep speech providers configurable, so the telephony path and the model path can evolve independently while the SBC heritage keeps the call edge stable.
Key Capabilities
- Connect any contact center or SIP trunk to any supported bot platform.
- Self-Service Live Hub versus Enterprise editions for different operating models.
- Bot targets spanning Azure, Lex on AWS, Google, and custom Bot API.
- HTTP and WebSocket Bot API modes for how your bot session is driven.
- Configurable STT and TTS from separate providers.
- SBC technology heritage for the telephony edge and session handling.
Why Teams Pick It
Teams pick VoiceAI Connect when they want to keep their trunks and contact centers and still connect them to the bot stack they choose.
Bandwidth
Bandwidth brings global SIP trunking together with Programmable Voice and BXML, so the telephony foundation and the programmable layer sit on one vendor path.
On Bandwidth, the bridge is SIP plus programmable media. Calls arrive on SIP trunks, Programmable Voice and BXML control the session, and StartStream opens a WebSocket media path into your AI stack in one or both directions.
Official OpenAI Realtime guides show both WebSocket and SIP patterns, and Transfer or REFER closes the loop when the bot should yield to a human.
Key Capabilities
- Global SIP trunking as the enterprise telephony foundation.
- Programmable Voice with BXML for session control.
- Media Streaming via StartStream over WebSocket, uni-directional or bi-directional.
- Official OpenAI Realtime guides for WebSocket and SIP integration patterns.
- Human handoff with Transfer and REFER.
- Supporting TTS, IVR, recording, and related contact-center features.
Why Teams Pick It
Teams pick Bandwidth when SIP trunking is already their standard and they want programmable media streams into voice AI with a clean handoff to humans.
So, How To Choose A Voice AI Telephony Gateway?
Start from the heritage that matches how you already run voice.
- Choose Telnyx when you want call control and assistants on one carrier stack.
- Choose AudioCodes VoiceAI Connect when any trunk or contact center must reach any bot with SBC-grade edge handling.
- Choose Bandwidth when SIP trunks plus programmable media streams and official real-time model guides are the priority.
Also weigh human handoff, how you configure speech providers, and whether you prefer a portal-built assistant, a Bot API connector, or a WebSocket media stream you own end to end.
The shared frame stays the same: answer or route, stream or adapt audio, run the model path, and transfer when a person should take over.
Your choice is which heritage makes that frame operational for your platform and contact-center teams.