SIP Trunks

Last updated September 4, 2026

Outbound SIP trunks (REGISTER or static peering)

# GET /sip/trunks

List configured SIP trunks

Responses

200 List of trunks

Field	Type		Description
`trunks`	array[object]	required

# POST /sip/trunks

Create an outbound SIP trunk (REGISTER or static peering)

Creates a typed SIP trunk. For type: "sip_register", VoiceBlender begins REGISTERing to the supplied registrar URI with digest auth, refreshes before expiry, and routes inbound INVITEs that arrive on that peer's socket plus outbound INVITEs whose from matches the AOR through the trunk. Set sip_register.outbound_proxy to send both the REGISTER and those INVITEs via a next-hop proxy instead of straight at the registrar; the Request-URI and digest authentication still target registrar_uri. It defaults to SIP_OUTBOUND_PROXY and is resolved at creation time, so the trunk snapshot reports the hop actually in effect. For type: "ip_ip", returns 501 (reserved, not yet implemented).

Request Body

Field	Type		Description
`type`	enum	required	Trunk type discriminator. Only `sip_register` is implemented today; `ip_ip` is reserved and returns 501. Values: `sip_register`, `ip_ip`
`app_id`	string	optional	Application identifier carried through to every event emitted by this trunk.
`sip_register`	object	optional	Required when type == "sip_register". Configures the outbound REGISTER (registrar URI, AOR, digest credentials, expiry).
`registrar_uri`	string	required	Upstream registrar SIP URI (e.g. "sip:pbx.example.com:5060" or "sips:pbx.example.com:5061"). Transport is taken from the URI: a "sips:" scheme or a ";transport=tls" parameter selects TLS, ";transport=tcp" selects TCP, otherwise UDP. Note that "transport" is a URI parameter (";"), not a URI header ("?") — RFC 3261 section 19.1.
`outbound_proxy`	string	optional	Next-hop SIP proxy for this trunk's REGISTER and for outbound INVITEs placed from its AOR, attached as a loose `Route` header (the Request-URI is left unchanged, and digest auth still targets `registrar_uri`). E.g. "sip:edge.example.com:5060;transport=tcp". Defaults to `SIP_OUTBOUND_PROXY`; when neither is set, requests go straight to `registrar_uri`.
`aor`	string	required	Address-of-record this trunk REGISTERs (e.g. "sip:alice@pbx.example.com"). Becomes the From URI on outbound REGISTER, and the From / P-Asserted-Identity host on outbound INVITEs placed `from` this AOR.
`username`	string	optional	Digest auth username. Defaults to the AOR user-part when empty.
`password`	string	required	Digest auth password. Required. Never returned in any response.
`contact_user`	string	optional	Override the user-part of the Contact header sent in REGISTER. Defaults to the AOR user-part.
`expires_seconds`	integer	optional	Requested registration lifetime in seconds. Clamped to [SIP_OUTBOUND_REGISTRATION_MIN_EXPIRES_SECONDS, SIP_OUTBOUND_REGISTRATION_MAX_EXPIRES_SECONDS]. Default: SIP_OUTBOUND_REGISTRATION_DEFAULT_EXPIRES_SECONDS (3600).
`tls_insecure_skip_verify`	boolean	optional	Accept this trunk's next-hop certificate without verifying it, for a `sips:` / `;transport=tls` registrar or outbound proxy whose certificate is self-signed, privately signed, or carries no SAN (`x509: certificate relies on legacy Common Name field`). Scoped to that peer's hostname — every other TLS peer is still verified in full, unlike the server-wide `SIP_TLS_INSECURE_SKIP_VERIFY`. Ignored (with a logged warning) when the next hop is not TLS, or when it is named by IP literal: such a dial sends no SNI and cannot be told apart from any other, so use `SIP_TLS_CA_FILE` or `SIP_TLS_INSECURE_SKIP_VERIFY` there. Prefer `SIP_TLS_CA_FILE` when the peer's CA can simply be trusted.
`ip_ip`	object	optional	Reserved for static-IP peering (no REGISTER). Not yet implemented; supplying this returns 501.
`peer_uri`	string	optional	Static peer SIP URI for IP-IP peering. Reserved; not yet implemented.

Responses

202 Trunk accepted; REGISTER runs asynchronously

Field	Type
`id`	string	required
`type`	string	required
`status`	string	required

400 Invalid JSON, missing required field, or unknown type

Field	Type		Description
`instance_id`	string	optional	Instance identifier
`error`	string	required	Error message

501 Trunk type reserved but not yet implemented (e.g. ip_ip)

Field	Type		Description
`instance_id`	string	optional	Instance identifier
`error`	string	required	Error message

# GET /sip/trunks/{id}

Get a single SIP trunk

Parameters

Name	In	Type		Description
`id`	path	string	required	Leg ID

Responses

200 Trunk view

Field	Type
`id`	string	required
`type`	string	required
`app_id`	string	optional
`status`	string	required
`last_error`	string	optional
`created_at`	string	required
`sip_register`	object	optional
`registrar_uri`	string	required
`outbound_proxy`	string	optional
`aor`	string	required
`username`	string	optional
`contact_uri`	string	optional
`requested_expires_seconds`	integer	required
`granted_expires_seconds`	integer	optional
`last_registered_at`	string	optional
`next_refresh_at`	string	optional
`call_id`	string	optional
`cseq`	integer	optional
`source_address`	string	optional
`tls_insecure_skip_verify`	boolean	optional
`ip_ip`	object	optional
`peer_uri`	string	optional

404 Trunk not found

Field	Type		Description
`instance_id`	string	optional	Instance identifier
`error`	string	required	Error message

# DELETE /sip/trunks/{id}

Unregister and remove a SIP trunk

Returns 202 Accepted; the unregister (REGISTER with Expires: 0) and final removal run asynchronously.

Parameters

Name	In	Type		Description
`id`	path	string	required	Leg ID

Responses

202 Trunk accepted for teardown

404 Trunk not found

Field	Type		Description
`instance_id`	string	optional	Instance identifier
`error`	string	required	Error message

Schemas

Objects used by the SIP Trunks endpoints above.

CreateTrunkRequest

Field	Type		Description
`type`	enum	required	Trunk type discriminator. Only `sip_register` is implemented today; `ip_ip` is reserved and returns 501. Values: `sip_register`, `ip_ip`
`app_id`	string	optional	Application identifier carried through to every event emitted by this trunk.
`sip_register`	object	optional	Required when type == "sip_register". Configures the outbound REGISTER (registrar URI, AOR, digest credentials, expiry).
`registrar_uri`	string	required	Upstream registrar SIP URI (e.g. "sip:pbx.example.com:5060" or "sips:pbx.example.com:5061"). Transport is taken from the URI: a "sips:" scheme or a ";transport=tls" parameter selects TLS, ";transport=tcp" selects TCP, otherwise UDP. Note that "transport" is a URI parameter (";"), not a URI header ("?") — RFC 3261 section 19.1.
`outbound_proxy`	string	optional	Next-hop SIP proxy for this trunk's REGISTER and for outbound INVITEs placed from its AOR, attached as a loose `Route` header (the Request-URI is left unchanged, and digest auth still targets `registrar_uri`). E.g. "sip:edge.example.com:5060;transport=tcp". Defaults to `SIP_OUTBOUND_PROXY`; when neither is set, requests go straight to `registrar_uri`.
`aor`	string	required	Address-of-record this trunk REGISTERs (e.g. "sip:alice@pbx.example.com"). Becomes the From URI on outbound REGISTER, and the From / P-Asserted-Identity host on outbound INVITEs placed `from` this AOR.
`username`	string	optional	Digest auth username. Defaults to the AOR user-part when empty.
`password`	string	required	Digest auth password. Required. Never returned in any response.
`contact_user`	string	optional	Override the user-part of the Contact header sent in REGISTER. Defaults to the AOR user-part.
`expires_seconds`	integer	optional	Requested registration lifetime in seconds. Clamped to [SIP_OUTBOUND_REGISTRATION_MIN_EXPIRES_SECONDS, SIP_OUTBOUND_REGISTRATION_MAX_EXPIRES_SECONDS]. Default: SIP_OUTBOUND_REGISTRATION_DEFAULT_EXPIRES_SECONDS (3600).
`tls_insecure_skip_verify`	boolean	optional	Accept this trunk's next-hop certificate without verifying it, for a `sips:` / `;transport=tls` registrar or outbound proxy whose certificate is self-signed, privately signed, or carries no SAN (`x509: certificate relies on legacy Common Name field`). Scoped to that peer's hostname — every other TLS peer is still verified in full, unlike the server-wide `SIP_TLS_INSECURE_SKIP_VERIFY`. Ignored (with a logged warning) when the next hop is not TLS, or when it is named by IP literal: such a dial sends no SNI and cannot be told apart from any other, so use `SIP_TLS_CA_FILE` or `SIP_TLS_INSECURE_SKIP_VERIFY` there. Prefer `SIP_TLS_CA_FILE` when the peer's CA can simply be trusted.
`ip_ip`	object	optional	Reserved for static-IP peering (no REGISTER). Not yet implemented; supplying this returns 501.
`peer_uri`	string	optional	Static peer SIP URI for IP-IP peering. Reserved; not yet implemented.

CreateTrunkResponse

Field	Type
`id`	string	required
`type`	string	required
`status`	string	required

Error

Field	Type		Description
`instance_id`	string	optional	Instance identifier
`error`	string	required	Error message

IPIPTrunkSpec

Field	Type		Description
`peer_uri`	string	optional	Static peer SIP URI for IP-IP peering. Reserved; not yet implemented.

IPIPTrunkView

Field	Type		Description
`peer_uri`	string	optional

SIPRegisterTrunkSpec

Field	Type		Description
`registrar_uri`	string	required	Upstream registrar SIP URI (e.g. "sip:pbx.example.com:5060" or "sips:pbx.example.com:5061"). Transport is taken from the URI: a "sips:" scheme or a ";transport=tls" parameter selects TLS, ";transport=tcp" selects TCP, otherwise UDP. Note that "transport" is a URI parameter (";"), not a URI header ("?") — RFC 3261 section 19.1.
`outbound_proxy`	string	optional	Next-hop SIP proxy for this trunk's REGISTER and for outbound INVITEs placed from its AOR, attached as a loose `Route` header (the Request-URI is left unchanged, and digest auth still targets `registrar_uri`). E.g. "sip:edge.example.com:5060;transport=tcp". Defaults to `SIP_OUTBOUND_PROXY`; when neither is set, requests go straight to `registrar_uri`.
`aor`	string	required	Address-of-record this trunk REGISTERs (e.g. "sip:alice@pbx.example.com"). Becomes the From URI on outbound REGISTER, and the From / P-Asserted-Identity host on outbound INVITEs placed `from` this AOR.
`username`	string	optional	Digest auth username. Defaults to the AOR user-part when empty.
`password`	string	required	Digest auth password. Required. Never returned in any response.
`contact_user`	string	optional	Override the user-part of the Contact header sent in REGISTER. Defaults to the AOR user-part.
`expires_seconds`	integer	optional	Requested registration lifetime in seconds. Clamped to [SIP_OUTBOUND_REGISTRATION_MIN_EXPIRES_SECONDS, SIP_OUTBOUND_REGISTRATION_MAX_EXPIRES_SECONDS]. Default: SIP_OUTBOUND_REGISTRATION_DEFAULT_EXPIRES_SECONDS (3600).
`tls_insecure_skip_verify`	boolean	optional	Accept this trunk's next-hop certificate without verifying it, for a `sips:` / `;transport=tls` registrar or outbound proxy whose certificate is self-signed, privately signed, or carries no SAN (`x509: certificate relies on legacy Common Name field`). Scoped to that peer's hostname — every other TLS peer is still verified in full, unlike the server-wide `SIP_TLS_INSECURE_SKIP_VERIFY`. Ignored (with a logged warning) when the next hop is not TLS, or when it is named by IP literal: such a dial sends no SNI and cannot be told apart from any other, so use `SIP_TLS_CA_FILE` or `SIP_TLS_INSECURE_SKIP_VERIFY` there. Prefer `SIP_TLS_CA_FILE` when the peer's CA can simply be trusted.

SIPRegisterTrunkView

Field	Type
`registrar_uri`	string	required
`outbound_proxy`	string	optional
`aor`	string	required
`username`	string	optional
`contact_uri`	string	optional
`requested_expires_seconds`	integer	required
`granted_expires_seconds`	integer	optional
`last_registered_at`	string	optional
`next_refresh_at`	string	optional
`call_id`	string	optional
`cseq`	integer	optional
`source_address`	string	optional
`tls_insecure_skip_verify`	boolean	optional

TrunkView

Field	Type
`id`	string	required
`type`	string	required
`app_id`	string	optional
`status`	string	required
`last_error`	string	optional
`created_at`	string	required
`sip_register`	object	optional
`registrar_uri`	string	required
`outbound_proxy`	string	optional
`aor`	string	required
`username`	string	optional
`contact_uri`	string	optional
`requested_expires_seconds`	integer	required
`granted_expires_seconds`	integer	optional
`last_registered_at`	string	optional
`next_refresh_at`	string	optional
`call_id`	string	optional
`cseq`	integer	optional
`source_address`	string	optional
`tls_insecure_skip_verify`	boolean	optional
`ip_ip`	object	optional
`peer_uri`	string	optional

TrunksListResponse

Field	Type		Description
`trunks`	array[object]	required