An AI voice agent gateway for legacy SIP

Voice agents are built for the web. OpenAI exposes GPT-Live-1 over SIP, but the contract is a web contract: TLS signalling on port 5061, SRTP media, an HTTPS webhook that must accept each incoming call with the model, voice and instructions, and a session the agent only runs while a client is attached to it. xAI's agents want TLS and a digest credential. None of that exists in a class-4 softswitch, most SBCs, or a PBX that has been in service for a decade.

1. Your switch sends the call to the ingress, over UDP or TCP with an early SDP offer, authorized by its IP address, as for any other route.
2. A routing rule picks a Voice AI destination: the agent provider, the project or agent identifier, and the agent's voice and instructions.
3. The platform originates the agent leg: TLS signalling, SRTP media, telephony codecs. For OpenAI, it accepts the call through the webhook it hosts and attaches the session. For xAI, it answers the digest challenge.
4. The switch gets a normal answer: plain RTP, a single route hop, a Contact on the platform. Its ACK, re-INVITEs and BYE are re-targeted to the agent.
5. The call is relayed, recorded and analyzed, and when either side hangs up, the other side is told at once.

The switch never sees a certificate, a crypto attribute, a webhook or a session. From its side, the agent is a carrier route that happens to answer every call.

Carriers and ITSPs

Offer AI answering, screening or after-hours agents to wholesale and retail customers from the softswitch you already run. Each customer gets their own destination, secrets and per-second metering, and you set the retail rate.

Contact centres

Put a GPT-Live-1 agent in front of a queue, a DID or an overflow route without touching the PBX's transport stack. Every agent conversation comes back recorded, transcribed and scored.

PBX and SBC operators

Divert flagged or unwanted callers to an agent instead of a human, or route a prefix to an agent for a pilot. The same platform screens the traffic for fraud.

Today: OpenAI's GPT-Live-1, the first voice model that behaves like a live conversation partner, the OpenAI Realtime models, and xAI's voice agents. Each is a Voice AI destination with its own connection rules. The list is published by the API and in the portal, and grows as providers are tested end to end.

• Stereo recording, caller on one channel, agent on the other.
• Transcript, verdict and red flags, as for a human-answered call.
• The SIP ladder and per-leg quality, with estimated MOS.
• The agent leg metered per second, shown on the record and on the invoice.
• The agent's own transcript of what it heard and said, on the destination.

Each destination has a call handling setting: full analysis, record only, or relay only. Relay only skips the recording, transcript, verdict and SIP log. The call is bridged and metered, and the record keeps the facts of the call. The default stays full analysis.

When the agent asks to transfer the caller, the platform checks the number against your account and places the new call itself through your routing, connects the caller to it and releases the agent. Your switch sees only the same call. The new leg is routed, recorded and billed like any other, and the call record shows the transfer, how far it got and the new call. A switch that handles transfers itself can be handed the SIP REFER instead, per destination. You can start a transfer yourself from the call page, the API or an MCP tool, and the keys a caller presses are on the record. An agent-initiated hang-up ends the call for the switch at once.

The connect any SBC to a voice agent guide takes a switch from nothing to a live agent call in four steps: whitelist the switch, add the destination, register the webhook, route a prefix. Provider setup details are in the SIP integration guide. Or start free with $5 credit and dial an agent from the web dialer first.