Telnyx X402 API
The x402 API from Telnyx — 3 operation(s) for x402.
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OpenAPI Specification
openapi: 3.2.0
info:
version: 2.0.0
x-latency-category: responsive
x-endpoint-cost: light
title: Telnyx X402 API
description: SIP trunking, SMS, MMS, Call Control and Telephony Data Services.
contact:
email: support@telnyx.com
servers:
- url: https://api.telnyx.com/v2
description: Version 2.0.0 of the Telnyx API
security:
- bearerAuth: []
tags:
- name: X402
paths:
/v1/chat/completions:
post:
operationId: x402_v1ChatCompletions
summary: Pay-per-call API via x402
description: OpenAI-compatible chat completions via Telnyx Inference — 13 open-weight models (MiniMax, Kimi, GLM, Llama, Qwen, Gemma) selected via body.model, from $0.002 to $0.150193 USDC per call. No API key, no signup, pay per request. Returns HTTP 402 with `payment-required` header; settle the x402 challenge to receive the response. No Telnyx API key required.
tags:
- X402
servers:
- url: https://x402.telnyx.com
description: x402 pay-per-call gateway
security: []
x-payment-info:
offers:
- intent: charge
method: x402
amount: '13850'
currency: '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913'
description: '0.01385 USDC per call via x402 on Base. Gateway: https://x402.telnyx.com/v1/chat/completions'
requestBody:
required: true
content:
application/json:
schema:
type: object
required:
- model
- messages
properties:
model:
type: string
description: Model slug — 13 open-weight models available (MiniMax, Kimi, GLM, Llama, Qwen, Gemma), e.g. "moonshotai/Kimi-K2.6". The 402 challenge quotes the per-model price.
messages:
type: array
items:
type: object
required:
- role
- content
properties:
role:
type: string
enum:
- system
- user
- assistant
- tool
content:
type: string
max_tokens:
type: integer
minimum: 1
description: Output token budget. Per-model caps apply and are quoted in the 402 challenge.
responses:
'200':
description: Successful completion (returned after payment settles).
content:
application/json:
schema:
$ref: '#/components/schemas/x402ChatCompletionResponse'
'402':
description: 'Payment Required — settle the x402 challenge described in the payment-required header. Gateway: https://x402.telnyx.com/v1/chat/completions. See `x-payment-info` for accepted payment offers.'
headers:
payment-required:
description: Base64-encoded x402v2 PaymentRequired envelope. Decode and settle the challenge per the x402 protocol.
schema:
type: string
content:
application/json:
schema:
$ref: '#/components/schemas/x402PaymentRequired'
/v1/audio/speech:
post:
operationId: x402_v1AudioSpeech
summary: Pay-per-call API via x402
description: Text-to-speech via Telnyx Inference (OpenAI-compatible /v1/audio/speech). 4,000+ voices across 9 providers, mp3 output, up to 3,000 characters. $0.000006 USDC per character metered ($0.002 minimum settle), or flat $0.018 exact per call. Returns HTTP 402 with `payment-required` header; settle the x402 challenge to receive the response. No Telnyx API key required.
tags:
- X402
servers:
- url: https://x402.telnyx.com
description: x402 pay-per-call gateway
security: []
x-payment-info:
offers:
- intent: charge
method: x402
amount: '18000'
currency: '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913'
description: '0.018 USDC per call via x402 on Base. Gateway: https://x402.telnyx.com/v1/audio/speech'
requestBody:
required: true
content:
application/json:
schema:
type: object
required:
- input
- voice
properties:
model:
type: string
description: Accepted for OpenAI SDK compatibility (e.g. "tts-1") but not forwarded — the voice id selects the engine.
input:
type: string
minLength: 1
maxLength: 3000
description: Text to synthesize. Upstream caps input at 3,000 characters.
voice:
type: string
description: OpenAI voice name (alloy, echo, …) or Telnyx voice id ("Provider.Model.VoiceId" — free catalog at GET /v1/audio/voices).
response_format:
type: string
enum:
- mp3
description: Output is always mp3.
responses:
'200':
description: MP3 audio (returned after payment settles).
content:
audio/mpeg:
schema:
type: string
format: binary
'402':
description: 'Payment Required — settle the x402 challenge described in the payment-required header. Gateway: https://x402.telnyx.com/v1/audio/speech. See `x-payment-info` for accepted payment offers.'
headers:
payment-required:
description: Base64-encoded x402v2 PaymentRequired envelope. Decode and settle the challenge per the x402 protocol.
schema:
type: string
content:
application/json:
schema:
$ref: '#/components/schemas/x402PaymentRequired'
/v1/audio/transcriptions:
post:
operationId: x402_v1AudioTranscriptions
summary: Pay-per-call API via x402
description: Speech-to-text via Telnyx Inference (OpenAI-compatible /v1/audio/transcriptions, multipart). Whisper large-v3-turbo, 100 languages, wav/mp3 up to 5 min / 12 MB. $0.003 USDC per minute metered per second ($0.002 minimum settle), or flat $0.015 exact per call. Returns HTTP 402 with `payment-required` header; settle the x402 challenge to receive the response. No Telnyx API key required.
tags:
- X402
servers:
- url: https://x402.telnyx.com
description: x402 pay-per-call gateway
security: []
x-payment-info:
offers:
- intent: charge
method: x402
amount: '15000'
currency: '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913'
description: '0.015 USDC per call via x402 on Base. Gateway: https://x402.telnyx.com/v1/audio/transcriptions'
requestBody:
required: true
content:
multipart/form-data:
schema:
type: object
required:
- file
properties:
file:
type: string
format: binary
description: Audio file (wav/mp3), up to 5 minutes / 12 MB.
model:
type: string
enum:
- whisper-1
- whisper-large-v3-turbo
- openai/whisper-large-v3-turbo
description: All aliases of openai/whisper-large-v3-turbo.
response_format:
type: string
enum:
- json
- verbose_json
language:
type: string
prompt:
type: string
maxLength: 1024
temperature:
type: number
minimum: 0
maximum: 1
responses:
'200':
description: Transcription (returned after payment settles). `verbose_json` adds duration and segment timestamps.
content:
application/json:
schema:
type: object
required:
- text
properties:
text:
type: string
duration:
type: number
description: Audio duration in seconds (verbose_json only).
segments:
type: array
items:
type: object
description: Segment timestamps (verbose_json only).
'402':
description: 'Payment Required — settle the x402 challenge described in the payment-required header. Gateway: https://x402.telnyx.com/v1/audio/transcriptions. See `x-payment-info` for accepted payment offers.'
headers:
payment-required:
description: Base64-encoded x402v2 PaymentRequired envelope. Decode and settle the challenge per the x402 protocol.
schema:
type: string
content:
application/json:
schema:
$ref: '#/components/schemas/x402PaymentRequired'
components:
schemas:
x402PaymentRequired:
type: object
description: x402 v2 Payment Required envelope. Returned by the x402 facilitator gateway when payment is required to access this operation. The same envelope is returned as the response body and base64-encoded in the `payment-required` HTTP response header.
required:
- x402Version
- error
- accepts
properties:
x402Version:
type: integer
const: 2
description: x402 protocol version. Always 2.
error:
type: string
description: Human-readable error string (e.g. 'Payment required').
resource:
type: object
description: The paid resource the client attempted to access.
properties:
url:
type: string
format: uri
method:
type: string
enum:
- GET
- POST
description:
type: string
mimeType:
type: string
accepts:
type: array
description: Accepted payment methods, in preference order.
items:
type: object
required:
- scheme
- network
- amount
- asset
- payTo
properties:
scheme:
type: string
network:
type: string
amount:
type: string
asset:
type: string
payTo:
type: string
maxTimeoutSeconds:
type: integer
extra:
type: object
additionalProperties: true
extensions:
type: object
description: Vendor-defined extensions (e.g. catalog URLs, headers).
additionalProperties: true
x402ChatCompletionResponse:
type: object
description: OpenAI-compatible chat completion response. Returned by the x402 gateway after payment settles. Schema is the minimal subset of the OpenAI chat-completions response that downstream clients rely on.
required:
- id
- object
- choices
properties:
id:
type: string
description: Unique identifier for the completion.
object:
type: string
const: chat.completion
choices:
type: array
description: Generated completion choices (typically one).
items:
type: object
required:
- index
- message
- finish_reason
properties:
index:
type: integer
minimum: 0
message:
type: object
required:
- role
- content
properties:
role:
type: string
enum:
- system
- user
- assistant
- tool
content:
type: string
finish_reason:
type: string
description: Why generation stopped (e.g. 'stop', 'length', 'tool_calls').
usage:
type: object
description: Token usage for the request.
properties:
prompt_tokens:
type: integer
minimum: 0
completion_tokens:
type: integer
minimum: 0
total_tokens:
type: integer
minimum: 0
securitySchemes:
BearerAuth:
type: http
scheme: bearer
bearerFormat: API key
description: 'Telnyx API key supplied as `Authorization: Bearer <token>`. In production, auth may be validated by the API gateway and forwarded via Telnyx auth headers.'
Payment:
type: apiKey
in: header
name: Authorization
description: 'Machine Payment Protocol credential used on paid retries, sent as `Authorization: Payment ...`. Obtained by paying a challenge returned in the `WWW-Authenticate` header of a 402 response. This is not a Telnyx API key; initial challenge requests use standard bearer authentication instead.'
agent-memory_bearerAuth:
type: http
scheme: bearer
description: Telnyx API key
bearerAuth:
type: http
scheme: bearer
branded-calling_bearerAuth:
type: http
scheme: bearer
description: Telnyx API key. Generate one at https://portal.telnyx.com/#/app/api-keys.
collections_bearerAuth:
type: http
scheme: bearer
description: Telnyx API key. Collections and results are automatically scoped to the authenticated user's organization.
number-reputation_bearerAuth:
type: http
scheme: bearer
description: Telnyx API key. Generate one at https://portal.telnyx.com/#/app/api-keys.
oauthClientAuth:
type: oauth2
flows:
clientCredentials:
tokenUrl: https://api.telnyx.com/v2/oauth/token
scopes:
admin: Administrative access to Telnyx resources
authorizationCode:
authorizationUrl: https://api.telnyx.com/v2/oauth/authorize
tokenUrl: https://api.telnyx.com/v2/oauth/token
refreshUrl: https://api.telnyx.com/v2/oauth/token
scopes:
admin: Administrative access to Telnyx resources
description: OAuth 2.0 authentication for Telnyx API and MCP integrations
outbound-voice-profiles_bearerAuth:
type: http
scheme: bearer
bearerFormat: JWT
pronunciation-dicts_bearerAuth:
type: http
scheme: bearer
description: Telnyx API v2 key. Obtain from https://portal.telnyx.com
rcs-registration_bearerAuth:
type: http
scheme: bearer
bearerFormat: API key
stored-payment-transactions_bearerAuth:
type: http
scheme: bearer
bearerFormat: JWT
transcriptions-search_bearerAuth:
type: http
scheme: bearer
description: Telnyx API key. Results are automatically scoped to the authenticated user's organization.
web-search_bearerAuth:
type: http
scheme: bearer
description: Telnyx API key
x-service-info:
categories:
- communication
- developer-tools
docs:
apiReference: https://developers.telnyx.com
homepage: https://telnyx.com
llms: https://telnyx.com/llms.txt