> ## Documentation Index > Fetch the complete documentation index at: https://docs.rumik.ai/llms.txt > Use this file to discover all available pages before exploring further. # assign an agent to a sip trunk > choose which agent answers calls to the number (UUID or handle). the number is detached from any previous agent; `agentId: null` unassigns. only a deployed agent can take a number. ## OpenAPI ````yaml /openapi.json post /v1/sip-trunks/{trunk_id}/assign openapi: 3.1.0 info: title: silk api version: 1.0.0 description: >- rumik ai's speech api. synthesize speech with the expressive `muga` model, the faster `mulberry` model or the multilingual `mulberry-1.6` model over http or a streaming websocket session, run conversational voice agents over webrtc, a realtime pcm socket or the phone, and manage everything the agents playground does — agents, voices, variables, tools, phone numbers, sip trunks and outbound calls — with the same api key. contact: name: rumik ai url: https://rumik.ai servers: - url: https://silk-api.rumik.ai description: production security: - bearerAuth: [] tags: - name: speech description: text-to-speech over HTTP and WebSocket. - name: voice agents description: start calls with a deployed agent from your own app. - name: agents description: build, configure, deploy and inspect your agents. - name: calls description: place outbound phone calls and read call history. - name: voices description: the voices, languages and styles an agent may use. - name: variables description: account-wide `{name}` prompt variables and their defaults. - name: tools description: HTTP tools agents call before or during a call. - name: phone numbers description: 'numbers rented through rumik: search, rent, connect, release.' - name: sip trunks description: bring your own numbers over SIP. paths: /v1/sip-trunks/{trunk_id}/assign: post: tags: - sip trunks summary: assign an agent to a sip trunk description: >- choose which agent answers calls to the number (UUID or handle). the number is detached from any previous agent; `agentId: null` unassigns. only a deployed agent can take a number. operationId: assignSipTrunk parameters: - name: trunk_id in: path required: true schema: type: string format: uuid description: the SIP trunk's id. requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/AssignAgentRequest' examples: default: value: agentId: ua_fe3277d8 responses: '200': description: ok. content: application/json: schema: $ref: '#/components/schemas/SipTrunk' examples: default: value: id: 019f7c10-2b4e-7d5f-8a6b-7c8d9e0f1a2b phoneNumber: '+919876543210' displayName: support line terminationUri: sip:pstn.example-carrier.in authUsername: silk hasAuth: true originationUri: sip:sip.silk.rumik.ai;transport=tcp assignedAgentId: 019f6a2e-7c1d-7b3a-9e4f-1a2b3c4d5e6f assignedAgentName: support status: active createdAt: '2026-09-11T10:00:00Z' updatedAt: '2026-09-11T10:00:00Z' '401': description: >- `unauthorized` — key missing, malformed, unknown, revoked or expired. content: application/json: schema: $ref: '#/components/schemas/Error' examples: unauthorized: value: error: Invalid API key code: unauthorized '403': description: '`forbidden_scope` — the key was created without the `agent` scope.' content: application/json: schema: $ref: '#/components/schemas/Error' examples: forbidden_scope: value: error: This API key lacks the 'agent' scope code: forbidden_scope '404': description: >- `sip_trunk_not_found` — no such SIP trunk on this account (or it cannot place calls). `agent_not_found` — no such agent on this account. content: application/json: schema: $ref: '#/components/schemas/Error' examples: sip_trunk_not_found: value: error: Phone number not found code: sip_trunk_not_found agent_not_found: value: error: Agent not found code: agent_not_found '409': description: >- `agent_not_deployed` — only a deployed agent (one with a live version) can answer a number or take a call. content: application/json: schema: $ref: '#/components/schemas/Error' examples: agent_not_deployed: value: error: Deploy the agent before assigning a phone number to it code: agent_not_deployed '429': description: >- `rate_limited` — the key's per-minute budget is spent. `Retry-After` says how long to wait; the body carries `limit` and `current`. content: application/json: schema: $ref: '#/components/schemas/Error' examples: rate_limited: value: error: Rate limit exceeded code: rate_limited limit: 100 current: 101 headers: Retry-After: description: seconds to wait before retrying (per-key rate limit only). schema: type: integer components: schemas: AssignAgentRequest: properties: agentId: anyOf: - type: string maxLength: 64 - type: 'null' description: the agent's UUID or `ua_…` handle; `null` unassigns. type: object title: AssignAgentRequest description: Which agent answers a number; ``null`` detaches it. SipTrunk: properties: id: type: string format: uuid description: the trunk's id — `fromTrunkId` on `POST /v1/calls`. phoneNumber: type: string description: the number, E.164. displayName: type: string terminationUri: type: string authUsername: anyOf: - type: string - type: 'null' hasAuth: type: boolean description: whether credentials are stored. originationUri: anyOf: - type: string - type: 'null' description: the SIP address your carrier must send inbound calls to. assignedAgentId: anyOf: - type: string format: uuid - type: 'null' description: the agent answering the number, or null. assignedAgentName: anyOf: - type: string - type: 'null' description: that agent's name. status: type: string description: '`active`.' createdAt: type: string format: date-time updatedAt: type: string format: date-time type: object required: - id - phoneNumber - displayName - terminationUri - hasAuth - status - createdAt - updatedAt title: SipTrunk description: one of your own numbers registered on the platform. Error: type: object properties: error: type: string description: human-readable error message. code: type: string description: machine-readable error code. securitySchemes: bearerAuth: type: http scheme: bearer description: >- your rumik api key, e.g. `rk_live_...`. create one in the rumik dashboard. ````