BYO SIP Trunking

BYO SIP trunking lets you connect carrier trunks directly to Burki while still using Burki assistants, routing, transcripts, recordings, billing, and observability.

Architecture

The bridge handles SIP signaling and audio adaptation. Burki handles assistant lookup, call state, streaming, transcripts, and AI orchestration.

When to Use BYO SIP

You already have carrier contracts or number inventory.
You need SIP-level control over routing, failover, or origination.
You want a self-hosted or hybrid telephony path.
You need to keep carrier billing outside Burki managed carrier costs.

Setup Flow

Create SIP trunks

Add one or more trunks through the SIP Trunks API or dashboard. Each trunk includes gateway, username, password, priority, enabled status, and registration behavior.

Sync to SIP bridge

Burki pushes enabled trunk configuration to the SIP bridge. The bridge generates FreeSWITCH gateway config and reloads SIP profiles.

Assign numbers

Assign organization phone numbers to the relevant sip_trunk_id so outbound calls and routing resolve the correct carrier path.

Test calls

Place inbound and outbound test calls, then inspect call logs, transcripts, recordings, and SIP bridge logs.

PBX Network Setup

For the current hosted SIP bridge, configure your PBX/carrier to talk to Burki at:

Burki SIP bridge IP: 52.21.157.171
SIP signaling: UDP/TCP 5060
SIP TLS: TCP 5061, if your trunk uses TLS
RTP media: UDP 10000-20000

Allowlist 52.21.157.171 on your PBX firewall and SIP ACLs for both signaling and media. Do not expose your PBX to all public SIP traffic if your PBX supports source IP restrictions.

Direction	PBX/Carrier Requirement	Burki Requirement
Inbound calls to Burki	Send INVITEs to `52.21.157.171:5060` or your assigned bridge address. Allow RTP from `52.21.157.171` on UDP `10000-20000`.	Phone number must exist in Burki and be assigned to an assistant or flow.
Outbound calls from Burki	Accept SIP INVITEs and RTP from `52.21.157.171`. If Burki registers to your PBX, allow the configured SIP username from this bridge IP.	SIP trunk `gateway` should be your PBX/carrier host and port, such as `pbx.example.com:5060` or `138.197.131.209:6061`.
Registration-based trunks	Enable registration on the PBX for the username/password you give Burki.	Set `register: true` on the SIP trunk.
IP-auth trunks	Allow `52.21.157.171` as a trusted peer.	Set `register: false` and configure the gateway host/IP.

Example PBX-facing trunk record:

{
  "name": "Customer PBX",
  "gateway": "138.197.131.209:6061",
  "username": "9228",
  "password": "sip-password",
  "priority": 1,
  "enabled": true,
  "register": true,
  "provider": "freepbx"
}

In this example, Burki registers to the customer’s PBX at 138.197.131.209:6061 with username 9228, while the customer’s PBX sends inbound calls to Burki at 52.21.157.171:5060.

Multiple DIDs on One PBX Extension

Burki routes calls by the real called phone number, not by short extension digits alone. Forwarding many numbers to one PBX extension works only if the PBX preserves the original called DID in SIP signaling. When a PBX forwards several DIDs to one extension, ask it to include one of these headers on the INVITE to Burki:

Header / Field	Purpose
`Diversion`	Preferred for forwarded calls; include the original called DID.
`History-Info`	Standard history header that can carry the original called number.
`X-Original-Called`, `X-Original-Number`, `X-Forwarded-To`, or `X-Original-To`	Accepted custom headers for PBX-specific setups.
`P-Called-Party-ID`	Accepted when the carrier/PBX uses this to preserve called-party identity.
Request-URI or `To` user	Also works if the PBX sends the real E.164 DID instead of only the short extension.

Example forwarded INVITE target that works:

INVITE sip:9228@52.21.157.171:5060
Diversion: <sip:+16478491000@pbx.example.com>;reason=unconditional

Without one of those headers, a call that arrives only as sip:9228@52.21.157.171 is ambiguous once more than one Burki number is assigned behind that extension. Burki will not guess between multiple assigned DIDs because guessing can send the caller to the wrong AI agent. For FreePBX, enable Diversion/History-Info or add a custom header on each inbound route before forwarding to the Burki trunk. After the PBX sends a test call, Burki support can confirm whether the original DID is visible in the captured INVITE.

Routing and Failover

SIP trunks have a priority field. Lower values are preferred first. Disable a trunk to remove it from routing without deleting credentials.

{
  "name": "Primary Carrier",
  "gateway": "sip.example-carrier.com",
  "username": "sip-user",
  "password": "sip-password",
  "priority": 1,
  "enabled": true,
  "register": true,
  "provider": "example-carrier"
}

Bridge Sync

The backend syncs organization SIP config to the bridge using:

POST {SIP_BRIDGE_URL}/api/sync-organization
Authorization: Bearer {SIP_BRIDGE_API_KEY}

The bridge stores/generated gateway configuration and reloads FreeSWITCH. A successful API response from Burki means the org config was updated and sync was attempted; check bridge logs for FreeSWITCH reload failures.

API References

Troubleshooting

Symptom	Check
Trunk does not register	Gateway, username/password, `register`, bridge FreeSWITCH logs
Calls route through the wrong carrier	Phone number `sip_trunk_id`, trunk `priority`, enabled status
Sync succeeds but calls fail	Bridge reload logs, generated gateway XML, carrier ACL/auth rules
Audio format issues	SIP bridge audio adapter logs and codec settings

Getting Started

Core Concepts

AI Providers

Features

Advanced

Help & Resources

Architecture

When to Use BYO SIP

Setup Flow

PBX Network Setup

Multiple DIDs on One PBX Extension

Routing and Failover

Bridge Sync

API References

Troubleshooting

​Architecture

​When to Use BYO SIP

​Setup Flow

​PBX Network Setup

​Multiple DIDs on One PBX Extension

​Routing and Failover

​Bridge Sync

​API References

​Troubleshooting

Architecture

When to Use BYO SIP

Setup Flow

PBX Network Setup

Multiple DIDs on One PBX Extension

Routing and Failover

Bridge Sync

API References

Troubleshooting