SIP Trunking

A SIP Trunk connects Teler to your own SIP infrastructure (a PBX, SBC, softswitch, or an AI voice platform) over SIP. It defines how Teler authenticates and routes SIP calls to and from that infrastructure, in both directions: inbound origination and outbound termination.

Trunks are created and managed in the Teler dashboard, or programmatically using the SIP Trunk API, the Python SDK, or the Node SDK

Tip

Use a Voice App when you want Teler to answer a number and run a programmable Call Flow you host. Use a SIP Trunk when you want to interconnect Teler with your own SIP system, or with managed voice AI platforms (e.g., ElevenLabs, Vapi, etc) that expose a SIP endpoint. They’re independent paths, and you can run both from the same account.

Configure a trunk

Click Create Trunk in the dashboard and fill in these fields:

Field	Required	Description
Name	yes	Internal label shown in the dashboard. Example: Production Trunk.
Domain Name	yes	Unique subdomain assigned to the trunk. All outbound calls route to this domain (a.k.a. the Termination URL). Alphanumeric and hyphens only.
Call Status URL	no	HTTPS endpoint that receives webhook events.
Secret	no	Signing secret used for HMAC signatures on webhooks. Rotatable without downtime.
Channel Limit	no	Maximum concurrent calls. Defaults to null; purchase more as needed. If channel_limit is null, the account-level channel limit applies instead.
Recording	no	When enabled, all call audio is recorded and delivered via recording events.
Transport Type	yes	Controls transport encryption. See below.
Webhook API version	no	Pin the webhook payload shape to 2025-08-01 or 2026-06-01. See API versioning.

Transport Type

Controls the protocol used for SIP signaling and media:

Transport	Port	Signaling	Media
TLS/SRTP	5061	SIP over TLS (encrypted)	SRTP (encrypted)
TCP	5060	SIP over TCP (unencrypted)	RTP (unencrypted)
UDP	5060	SIP over UDP (unencrypted)	RTP (unencrypted)

TLS + SRTP is recommended for any trunk carrying customer PII.

Note

SIP UDP only supports credential-based authentication; IP based authentication is not available for this transport. To use UDP, you must also share your origination IP with the Teler team in advance so it can be whitelisted.

Outbound authentication

Every trunk authenticates outbound calls one of two ways:

Method	Use when	How it’s configured
IP	Calls originate from fixed, static IP addresses.	Create an IP ACL (Access Control List) once, then assign it to multiple trunks. Calls from IPs in the ACL are accepted without credentials.
Credential	Your SIP system authenticates via username and password.	Set the username and password in the SIP trunk; your SIP client presents them on each INVITE.

Caution

IP authentication is not suitable for dynamic or cloud-based environments where your SIP client’s egress IP may change. Prefer credential authentication in those cases.

Inbound routing

Inbound routing tells Teler where to deliver calls that arrive on the trunk. Configure a route with:

Field	Required	Description
Name	yes	Internal label for the route.
SIP URL	yes	The SIP URL where Teler should forward inbound calls (a.k.a. the Origination URL). Provided by your downstream platform (AI provider, PBX, SBC, or softswitch). Example: sip:sip.rtc.elevenlabs.io:5061.
SIP User	no	SIP username to present to the destination, if your downstream platform requires one. The complete inbound SIP URL will become sip:<sip_user>@<sip_url>:<port>

Tip

By default, the inbound SIP URL is sip:<number>@<sip_url>:<port>, where <number> is the dialed number. If you set sip_user, that value replaces the number. Some downstream platforms require a unique identifier instead of the dialed number to route calls correctly. Set sip_user only if your platform requires this.

Next steps

Network requirements Teler IP addresses, ports, and protocols to allow on your firewall.

Call events Lifecycle webhooks delivered to your Call Status URL.

API versioning Pin your trunk to 2025-08-01 or 2026-06-01.

Signing & verification HMAC-SHA256 signature verification for the trunk's webhook secret.