SIP Trunking
Connect your voice infrastructure to Callr over SIP
A SIP trunk is a direct voice connection between your systems and ours — SIP for signaling, RTP for media. Keep your PBX, SBC, or contact center, and give every call access to Callr numbers, call flows, AI, and analytics. All on a carrier network we own.
Your infrastructure
- PBX / SBC
- Contact center
- AI voice agent
Callr platform
- Numbers (DIDs)
- Callr Actions
- AI toolkit
- REST API & webhooks
Both directions
Calls in, calls out — same trunk
A trunk carries traffic both ways, so Callr can sit in front of your stack, behind it, or in the middle.
Inbound — into Callr
External systems send calls into Callr to be routed, tracked, or processed with AI — your carrier or PBX delivers the call, Callr takes it from there.
Outbound — to your systems
Callr sends calls to your PBX, contact center, or AI system — from any Callr number, scenario, or API call.
Why trunk into Callr
One trunk, the whole platform
Anything connected over SIP gets what every Callr number gets: programmable flows, the AI toolkit, and clean data out.
Numbers in 220+ countries
Attach local, national, and toll-free numbers (DIDs) to your trunk and go live in seconds.
Programmable routing with Callr Actions
Put a YAML scenario in front of your trunk — IVR, business hours, failover, whisper — without touching your PBX.
AI on every call
Record, transcribe, summarize, and extract structured data from the calls crossing the trunk, then push it to your stack.
One source of truth for analytics
Every call is logged and available in real time — pull it from the REST API or receive webhooks straight into your CRM and BI.
Use cases
Where a trunk fits
SIP trunking is for teams that already run voice infrastructure — and want Callr’s programmable layer around it.
Call center integration
Agents stay on the platform they know; Callr routes, tracks, and applies AI to every conversation on the way in or out.
Keep your own PBX or SBC
No forklift migration: your infrastructure stays where it is, and Callr becomes the programmable voice layer in front of it.
Bridge external systems
Dial SIP URIs, transfer calls between platforms, and connect conferencing systems — without porting a single number.
Real-time AI voice agents
Route callers to ElevenLabs, Vapi, or the OpenAI Realtime API over native SIP — and hand off to a human at any point.
Under the hood
Interoperable by design
Standard SIP, standard formats, no lock-in — if your equipment speaks SIP, it speaks Callr.
UDP, TCP & TLS transports
SIP over UDP or TCP on port 5060, or TLS on 5061 — whichever your equipment prefers.
Encrypted end to end
TLS for signaling and SRTP for media keep every conversation private in transit.
EU & US points of presence
Regional gateways — eu.sip.callr.com and usa.sip.callr.com — keep media close and latency low.
E.164 number format
Standards-compliant international format on every INVITE — no proprietary dial plans.
Our own carrier network
Callr is a registered carrier running its own encrypted network across 220+ countries — not a reseller of someone else’s minutes.
Managed via REST API & webhooks
Provision numbers, control calls, and consume call events with the same API that runs the rest of Callr.
Endpoints, IP ranges, and configuration examples live in the docs. Read the docs →
Bring your voice stack to Callr
Start free and set up your trunk today — or read the docs for endpoints and configuration.