Integrations · SIP / PSTN

SIP AI voice agent

Connect Nexora Voice to any SIP trunk or PSTN carrier through a standards-based SIP integration. The agent runs full-duplex audio with sub-second latency, supports DTMF (touch-tone) input, and handles G.711 and Opus codecs. Multi-region deployment keeps audio local to your carrier — calls in Auckland route through New Zealand, calls in London route through Europe. No vendor lock-in: SIP is the protocol-level integration, not a particular vendor.

How it works

Three steps to ship SIP / PSTN in your pilot

STEP 1

Point your SIP trunk

Configure your SIP trunk to route inbound calls to the Nexora agent endpoint via SIP INVITE. Authenticate with mutual TLS or IP allowlisting. No carrier-side custom development required — standard SIP is enough.

STEP 2

Negotiate codec and routing

The agent negotiates G.711 or Opus per the trunk's preferences and selects the regional Nexora point-of-presence closest to your carrier. Audio path stays inside the locked-market region (NZ/AU/US/UK/EU).

STEP 3

Transfer or hand off

When the conversation needs a human, the agent issues a SIP REFER to transfer the call to your contact-centre queue. The transcript and signal events are delivered alongside via webhook so the human picks up context-aware.

What teams use it for

Common SIP / PSTN use cases

  • Inbound call deflection on a corporate SIP trunk, with call transfer to a human queue via SIP REFER when escalation is needed.

  • Outbound dialer campaigns originating from your PSTN carrier, with the same agent persona running across all calls.

  • Carrier-agnostic deployments that avoid vendor lock-in: SIP is the integration, the carrier is interchangeable.

Code preview

SIP — INVITE payload from carrier to Nexora

HTTP
INVITE sip:agent@nexoralabs.co.nz SIP/2.0
Via: SIP/2.0/TLS carrier.example.com:5061
From: "+64 ..." <sip:+64...@carrier.example.com>
To: <sip:agent@nexoralabs.co.nz>
Content-Type: application/sdp

v=0
m=audio 49170 RTP/AVP 0 8 109
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:109 opus/48000/2

Stylised example — not a runnable script. Endpoints, payload shapes, and authentication are documented in the integration runbook shipped during the pilot.

Frequently asked questions

Common questions

Which SIP trunk providers are supported?

Any standards-compliant SIP trunk. We've deployed against the major NZ, AU, US, UK, and EU carriers — both incumbents and CPaaS providers. SIP is the protocol; the carrier is your choice. We don't require a particular vendor, and we don't impose minimums on your existing carrier relationship.

Does the SIP integration support DTMF input?

Yes. DTMF (touch-tone) input is supported over RFC 2833 / RFC 4733 in-band signalling. The agent can prompt for a reference number or account ID and accept it via key-press if the customer prefers, or accept it spoken — whichever they choose, the same code path handles it.

Where is the audio media path?

The Nexora audio plane runs in points-of-presence in the five locked markets (NZ, AU, US, UK, EU). The agent selects the closest PoP to your carrier, so audio stays inside the region wherever possible. Multi-region routing rules let you pin audio to a specific region for residency requirements.

Can the agent hand off to a SIP-based contact centre?

Yes. The agent issues a SIP REFER (RFC 3515) to transfer the call to your contact-centre queue, your switchboard, or a specific agent extension. The transcript and signal events are delivered alongside via webhook so the human picks up the conversation with full context.

Ready to wire SIP / PSTN into your pilot?

Pilot in 14 days. Live in 30.

A 30-minute scoping call. We bring the SIP / PSTN integration patterns. You bring the system credentials and the first use case.

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