FreJun Teler

FreJun Teler is a developer-first programmable voice/telephony API (CPaaS) that handles carriers, phone numbers, and real-time audio streaming so developers can connect AI models (STT/LLM/TTS) to live phone calls. It offers real-time bidirectional audio over WebSocket (L16/8000 Hz, sub-250ms latency) and programmable SIP trunking, with webhook event delivery and official Python (teler) and Node (@frejun/teler) SDKs.

FreJun Teler publishes 12 APIs on the APIs.io network, including Events API, Secrets API, SIP / Calls API, and 9 more. Tagged areas include programmable voice API, voice AI infrastructure, CPaaS, SIP Trunking, and telephony API.

The FreJun Teler catalog on APIs.io includes 1 event-driven AsyncAPI specification.

FreJun Teler’s developer surface includes documentation, API reference, engineering blog, pricing, signup flow, authentication, sandbox, and 25 more developer resources.

🌐 Visit website 📡 Source on GitHub

40.8/100 developing ▬ flat Agent 47/100 agent ready Front door AI 6/6 dominant Full breakdown ↓
scored 2026-10-04 · rubric v0.23.0

2 published contracts 1 MCP Servers

programmable voice APIvoice AI infrastructureCPaaS SIP Trunkingtelephony APIreal-time media streamingWebSocket audioCall Automationconversational AI infrastructure

Kin Score

Kin Score How this is scored →
scored 2026-10-04 · rubric v0.23.0

Composite quality — 40.8/100 · developing

Contract Quality 12.0 / 19

Developer Ergonomics 6.9 / 15

Access Clarity 3.4 / 15

Operational Transparency 3.3 / 10

Contract Governance 0.4 / 9

Discoverability 5.5 / 8

Regulatory Posture 2.6 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 47/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 6 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 6 / 6

Protected Resource Metadata 5 / 5

Registration Without a Human 6 / 6

Agentic Commerce Well-Known Document 0 / 5

Regulatory Posture applies to this provider. Its tags matched the Telecommunications regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

The six quality facets above are damped to 75 points between them, because the conditional facet above carries the other 25. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/frejun-teler: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 12

Individual APIs this provider publishes, each with its own machine-readable definition.

FreJun Teler Events API

Inspect the webhook events Teler generated for your account and redeliver any that your endpoint missed.

FreJun Teler Secrets API

Manage secret API keys used for authenticating requests. Create, rotate, and delete secrets — rotate periodically and keep them server-side.

FreJun Teler SIP / Calls API

Read calls that arrived or left over your SIP trunks (`st_`).

FreJun Teler SIP / IP Access Control Lists API

Named sets of source IPs or CIDR networks (`acl_`) that SIP trunks with `authentication_type: IP` authorise against. Attach one to many trunks and update it in a single place.

FreJun Teler SIP / Trunks API

SIP trunks connect Teler to your upstream carrier or PBX. Create, configure, and manage your trunks, or inspect which virtual numbers are assigned to each one.

FreJun Teler Utilities API

Fetch short-lived, signed download URLs for call recordings.

FreJun Teler Virtual Numbers API

Phone numbers that Teler provisions for your account. List, assign to a voice app or SIP trunk, unassign, or update individual numbers.

FreJun Teler Voice / Apps API

Voice apps are the configuration context for calls — they define webhook URLs, flows, and channel limits. Create and manage your voice apps here.

FreJun Teler Voice / Call Controls API

Act on a live call in real time — hang up, mute, send DTMF, or play audio. These actions are accepted asynchronously and return `202` with a `request_id`.

FreJun Teler Voice / Calls API

Place outbound calls and read call state. A **call** (`cs_`) is the top-level session; each party on it is a **leg** (`cl_`).

FreJun Teler Voice / Calls (legacy) API

Deprecated endpoints kept for backwards compatibility. Prefer the **Voice / Calls** endpoints for all new integrations.

FreJun Teler Voice / Operations API

Higher-level, multi-step operations on a live call, such as transferring it to a new destination.

Scroll for all 12

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

FreJun Teler MCP Server

MCP SERVER

Pricing Plans 1

Published pricing tiers and plan structures.

Frejun Teler Plans Pricing

0 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Frejun Teler Rate Limits

0 limits

RATE LIMITS

Event Specifications 1

AsyncAPI definitions for this provider's event-driven and streaming APIs.

Frejun Teler Webhooks

ASYNCAPI

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Frejun Teler Authentication

apiKey · 1 scheme

SECURITY

Frejun Teler Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Resources

Get Started 4

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

SignUp

SignUp

Login

Sandbox

Sandbox

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt

WellKnown

MCPServer

AgentSkill

Design & Contract 7

Pagination, idempotency, versioning, errors, and events

Conventions

Lifecycle

Conformance

Components

Webhooks

DataModel

ErrorCatalog

Scroll for all 7

Build 3

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Packages

Packages

SDKs

SDKs

Access & Security 2

Authentication, authorization, and security posture

Authentication

Authentication

DomainSecurity

DomainSecurity

Operate 3

Status, limits, changes, and where to get help

StatusPage

StatusPage

Deprecation

Deprecation

RateLimits

RateLimits

Commercial 4

Pricing, plans, and the legal terms of use

Pricing

TermsOfService

PrivacyPolicy

Plans

Company 2

The organization behind the API

Website

Website

Blog

Blog

Other 1

Properties that don't map to a standard resource type

Overlay

Overlay

Source (apis.yml)

aid: frejun-teler
name: FreJun Teler
description: FreJun Teler is a developer-first programmable voice/telephony API (CPaaS) that handles carriers, phone numbers,
  and real-time audio streaming so developers can connect AI models (STT/LLM/TTS) to live phone calls. It offers real-time
  bidirectional audio over WebSocket (L16/8000 Hz, sub-250ms latency) and programmable SIP trunking, with webhook event delivery
  and official Python (teler) and Node (@frejun/teler) SDKs.
type: Index
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
url: https://raw.githubusercontent.com/api-evangelist/frejun-teler/refs/heads/main/apis.yml
created: '2026-09-15'
modified: '2026-09-15'
tags:
- programmable voice API
- voice AI infrastructure
- CPaaS
- SIP Trunking
- telephony API
- real-time media streaming
- WebSocket audio
- Call Automation
- conversational AI infrastructure
tags_raw:
- programmable voice API
- voice AI infrastructure
- CPaaS
- SIP trunking
- telephony API
- real-time media streaming
- WebSocket audio
- call automation
- conversational AI infrastructure
apis:
- aid: frejun-teler:frejun-teler-events-api
  name: FreJun Teler Events API
  description: Inspect the webhook events Teler generated for your account and redeliver any that your endpoint missed.
  humanURL: https://frejun.com/docs/teler/
  baseURL: https://api.frejun.ai
  tags:
  - Event
  tags_raw:
  - Events
  properties:
  - type: OpenAPI
    url: openapi/frejun-teler-events-api-openapi.yml
  - type: Documentation
    url: https://frejun.com/docs/teler/
  - type: APIReference
    url: https://api.frejun.ai/redoc
  - type: Authentication
    url: authentication/frejun-teler-authentication.yml
  - type: Conventions
    url: conventions/frejun-teler-conventions.yml
  - type: ErrorCatalog
    url: errors/frejun-teler-problem-types.yml
  - type: DataModel
    url: data-model/frejun-teler-data-model.yml
  - type: Webhooks
    url: asyncapi/frejun-teler-webhooks.yml
- aid: frejun-teler:frejun-teler-secrets-api
  name: FreJun Teler Secrets API
  description: Manage secret API keys used for authenticating requests. Create, rotate, and delete secrets — rotate periodically
    and keep them server-side.
  humanURL: https://frejun.com/docs/teler/
  baseURL: https://api.frejun.ai
  tags:
  - Secrets
  properties:
  - type: OpenAPI
    url: openapi/frejun-teler-secrets-api-openapi.yml
  - type: Documentation
    url: https://frejun.com/docs/teler/
  - type: APIReference
    url: https://api.frejun.ai/redoc
  - type: Authentication
    url: authentication/frejun-teler-authentication.yml
  - type: Conventions
    url: conventions/frejun-teler-conventions.yml
  - type: ErrorCatalog
    url: errors/frejun-teler-problem-types.yml
  - type: DataModel
    url: data-model/frejun-teler-data-model.yml
  - type: Webhooks
    url: asyncapi/frejun-teler-webhooks.yml
- aid: frejun-teler:frejun-teler-sip-calls-api
  name: FreJun Teler SIP / Calls API
  description: Read calls that arrived or left over your SIP trunks (`st_`).
  humanURL: https://frejun.com/docs/teler/
  baseURL: https://api.frejun.ai
  tags:
  - SIP / Calls
  properties:
  - type: OpenAPI
    url: openapi/frejun-teler-sip-calls-api-openapi.yml
  - type: Documentation
    url: https://frejun.com/docs/teler/
  - type: APIReference
    url: https://api.frejun.ai/redoc
  - type: Authentication
    url: authentication/frejun-teler-authentication.yml
  - type: Conventions
    url: conventions/frejun-teler-conventions.yml
  - type: ErrorCatalog
    url: errors/frejun-teler-problem-types.yml
  - type: DataModel
    url: data-model/frejun-teler-data-model.yml
  - type: Webhooks
    url: asyncapi/frejun-teler-webhooks.yml
- aid: frejun-teler:frejun-teler-sip-ip-access-control-lists-api
  name: FreJun Teler SIP / IP Access Control Lists API
  description: 'Named sets of source IPs or CIDR networks (`acl_`) that SIP trunks with `authentication_type: IP` authorise
    against. Attach one to many trunks and update it in a single place.'
  humanURL: https://frejun.com/docs/teler/
  baseURL: https://api.frejun.ai
  tags:
  - SIP / IP Access Control Lists
  properties:
  - type: OpenAPI
    url: openapi/frejun-teler-sip-ip-access-control-lists-api-openapi.yml
  - type: Documentation
    url: https://frejun.com/docs/teler/
  - type: APIReference
    url: https://api.frejun.ai/redoc
  - type: Authentication
    url: authentication/frejun-teler-authentication.yml
  - type: Conventions
    url: conventions/frejun-teler-conventions.yml
  - type: ErrorCatalog
    url: errors/frejun-teler-problem-types.yml
  - type: DataModel
    url: data-model/frejun-teler-data-model.yml
  - type: Webhooks
    url: asyncapi/frejun-teler-webhooks.yml
- aid: frejun-teler:frejun-teler-sip-trunks-api
  name: FreJun Teler SIP / Trunks API
  description: SIP trunks connect Teler to your upstream carrier or PBX. Create, configure, and manage your trunks, or inspect
    which virtual numbers are assigned to each one.
  humanURL: https://frejun.com/docs/teler/
  baseURL: https://api.frejun.ai
  tags:
  - SIP Trunks
  tags_raw:
  - SIP / Trunks
  properties:
  - type: OpenAPI
    url: openapi/frejun-teler-sip-trunks-api-openapi.yml
  - type: Documentation
    url: https://frejun.com/docs/teler/
  - type: APIReference
    url: https://api.frejun.ai/redoc
  - type: Authentication
    url: authentication/frejun-teler-authentication.yml
  - type: Conventions
    url: conventions/frejun-teler-conventions.yml
  - type: ErrorCatalog
    url: errors/frejun-teler-problem-types.yml
  - type: DataModel
    url: data-model/frejun-teler-data-model.yml
  - type: Webhooks
    url: asyncapi/frejun-teler-webhooks.yml
- aid: frejun-teler:frejun-teler-utilities-api
  name: FreJun Teler Utilities API
  description: Fetch short-lived, signed download URLs for call recordings.
  humanURL: https://frejun.com/docs/teler/
  baseURL: https://api.frejun.ai
  tags:
  - Utilities
  properties:
  - type: OpenAPI
    url: openapi/frejun-teler-utilities-api-openapi.yml
  - type: Documentation
    url: https://frejun.com/docs/teler/
  - type: APIReference
    url: https://api.frejun.ai/redoc
  - type: Authentication
    url: authentication/frejun-teler-authentication.yml
  - type: Conventions
    url: conventions/frejun-teler-conventions.yml
  - type: ErrorCatalog
    url: errors/frejun-teler-problem-types.yml
  - type: DataModel
    url: data-model/frejun-teler-data-model.yml
  - type: Webhooks
    url: asyncapi/frejun-teler-webhooks.yml
- aid: frejun-teler:frejun-teler-virtual-numbers-api
  name: FreJun Teler Virtual Numbers API
  description: Phone numbers that Teler provisions for your account. List, assign to a voice app or SIP trunk, unassign, or
    update individual numbers.
  humanURL: https://frejun.com/docs/teler/
  baseURL: https://api.frejun.ai
  tags:
  - Virtual Numbers
  properties:
  - type: OpenAPI
    url: openapi/frejun-teler-virtual-numbers-api-openapi.yml
  - type: Documentation
    url: https://frejun.com/docs/teler/
  - type: APIReference
    url: https://api.frejun.ai/redoc
  - type: Authentication
    url: authentication/frejun-teler-authentication.yml
  - type: Conventions
    url: conventions/frejun-teler-conventions.yml
  - type: ErrorCatalog
    url: errors/frejun-teler-problem-types.yml
  - type: DataModel
    url: data-model/frejun-teler-data-model.yml
  - type: Webhooks
    url: asyncapi/frejun-teler-webhooks.yml
- aid: frejun-teler:frejun-teler-voice-apps-api
  name: FreJun Teler Voice / Apps API
  description: Voice apps are the configuration context for calls — they define webhook URLs, flows, and channel limits. Create
    and manage your voice apps here.
  humanURL: https://frejun.com/docs/teler/
  baseURL: https://api.frejun.ai
  tags:
  - Voice / Apps
  properties:
  - type: OpenAPI
    url: openapi/frejun-teler-voice-apps-api-openapi.yml
  - type: Documentation
    url: https://frejun.com/docs/teler/
  - type: APIReference
    url: https://api.frejun.ai/redoc
  - type: Authentication
    url: authentication/frejun-teler-authentication.yml
  - type: Conventions
    url: conventions/frejun-teler-conventions.yml
  - type: ErrorCatalog
    url: errors/frejun-teler-problem-types.yml
  - type: DataModel
    url: data-model/frejun-teler-data-model.yml
  - type: Webhooks
    url: asyncapi/frejun-teler-webhooks.yml
- aid: frejun-teler:frejun-teler-voice-call-controls-api
  name: FreJun Teler Voice / Call Controls API
  description: Act on a live call in real time — hang up, mute, send DTMF, or play audio. These actions are accepted asynchronously
    and return `202` with a `request_id`.
  humanURL: https://frejun.com/docs/teler/
  baseURL: https://api.frejun.ai
  tags:
  - Voice / Call Controls
  properties:
  - type: OpenAPI
    url: openapi/frejun-teler-voice-call-controls-api-openapi.yml
  - type: Documentation
    url: https://frejun.com/docs/teler/
  - type: APIReference
    url: https://api.frejun.ai/redoc
  - type: Authentication
    url: authentication/frejun-teler-authentication.yml
  - type: Conventions
    url: conventions/frejun-teler-conventions.yml
  - type: ErrorCatalog
    url: errors/frejun-teler-problem-types.yml
  - type: DataModel
    url: data-model/frejun-teler-data-model.yml
  - type: Webhooks
    url: asyncapi/frejun-teler-webhooks.yml
- aid: frejun-teler:frejun-teler-voice-calls-api
  name: FreJun Teler Voice / Calls API
  description: Place outbound calls and read call state. A **call** (`cs_`) is the top-level session; each party on it is
    a **leg** (`cl_`).
  humanURL: https://frejun.com/docs/teler/
  baseURL: https://api.frejun.ai
  tags:
  - voice-calls
  tags_raw:
  - Voice / Calls
  properties:
  - type: OpenAPI
    url: openapi/frejun-teler-voice-calls-api-openapi.yml
  - type: Documentation
    url: https://frejun.com/docs/teler/
  - type: APIReference
    url: https://api.frejun.ai/redoc
  - type: Authentication
    url: authentication/frejun-teler-authentication.yml
  - type: Conventions
    url: conventions/frejun-teler-conventions.yml
  - type: ErrorCatalog
    url: errors/frejun-teler-problem-types.yml
  - type: DataModel
    url: data-model/frejun-teler-data-model.yml
  - type: Webhooks
    url: asyncapi/frejun-teler-webhooks.yml
- aid: frejun-teler:frejun-teler-voice-calls-legacy-api
  name: FreJun Teler Voice / Calls (legacy) API
  description: Deprecated endpoints kept for backwards compatibility. Prefer the **Voice / Calls** endpoints for all new integrations.
  humanURL: https://frejun.com/docs/teler/
  baseURL: https://api.frejun.ai
  tags:
  - Voice / Calls (legacy)
  properties:
  - type: OpenAPI
    url: openapi/frejun-teler-voice-calls-legacy-api-openapi.yml
  - type: Documentation
    url: https://frejun.com/docs/teler/
  - type: APIReference
    url: https://api.frejun.ai/redoc
  - type: Authentication
    url: authentication/frejun-teler-authentication.yml
  - type: Conventions
    url: conventions/frejun-teler-conventions.yml
  - type: ErrorCatalog
    url: errors/frejun-teler-problem-types.yml
  - type: DataModel
    url: data-model/frejun-teler-data-model.yml
  - type: Webhooks
    url: asyncapi/frejun-teler-webhooks.yml
- aid: frejun-teler:frejun-teler-voice-operations-api
  name: FreJun Teler Voice / Operations API
  description: Higher-level, multi-step operations on a live call, such as transferring it to a new destination.
  humanURL: https://frejun.com/docs/teler/
  baseURL: https://api.frejun.ai
  tags:
  - Voice / Operations
  properties:
  - type: OpenAPI
    url: openapi/frejun-teler-voice-operations-api-openapi.yml
  - type: Documentation
    url: https://frejun.com/docs/teler/
  - type: APIReference
    url: https://api.frejun.ai/redoc
  - type: Authentication
    url: authentication/frejun-teler-authentication.yml
  - type: Conventions
    url: conventions/frejun-teler-conventions.yml
  - type: ErrorCatalog
    url: errors/frejun-teler-problem-types.yml
  - type: DataModel
    url: data-model/frejun-teler-data-model.yml
  - type: Webhooks
    url: asyncapi/frejun-teler-webhooks.yml
common:
- type: Website
  url: https://www.frejun.ai
- type: DeveloperPortal
  url: https://frejun.com/docs/teler/
- type: Documentation
  url: https://frejun.com/docs/teler/
- type: APIReference
  url: https://api.frejun.ai/redoc
- type: Blog
  url: https://frejun.com/teler-blog/
- type: Pricing
  url: https://frejun.com/teler/pricing/
- type: SignUp
  url: https://platform.frejun.ai/signup
- type: Login
  url: https://platform.frejun.ai/login
- type: TermsOfService
  url: https://frejun.com/terms/
- type: PrivacyPolicy
  url: https://frejun.com/privacy-policy/
- type: GitHubOrganization
  url: https://github.com/frejun-tech
- type: StatusPage
  url: https://frejun.statuspage.io
- type: LLMsTxt
  url: https://www.frejun.ai/llms.txt
- type: WellKnown
  url: well-known/frejun-teler-well-known.yml
- type: Authentication
  url: authentication/frejun-teler-authentication.yml
- type: DomainSecurity
  url: security/frejun-teler-domain-security.yml
- type: Conventions
  url: conventions/frejun-teler-conventions.yml
- type: Lifecycle
  url: lifecycle/frejun-teler-lifecycle.yml
- type: Deprecation
  url: lifecycle/frejun-teler-lifecycle.yml
- type: Conformance
  url: conformance/frejun-teler-conformance.yml
- type: MCPServer
  url: mcp/frejun-teler-mcp.yml
- type: AgentSkill
  url: skills/_index.yml
- type: Packages
  url: packages/frejun-teler-packages.yml
- type: SDKs
  url: packages/frejun-teler-packages.yml
- type: Components
  url: components/frejun-teler-components.yml
- type: Webhooks
  url: asyncapi/frejun-teler-webhooks.yml
- type: DataModel
  url: data-model/frejun-teler-data-model.yml
- type: ErrorCatalog
  url: errors/frejun-teler-problem-types.yml
- type: Overlay
  url: overlays/frejun-teler-openapi-overlay.yaml
- type: Sandbox
  url: sandbox/frejun-teler-sandbox.yml
- type: RateLimits
  url: rate-limits/frejun-teler-rate-limits.yml
- type: Plans
  url: plans/frejun-teler-plans-pricing.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
x-enrichment:
  date: '2026-09-15'
  status: enriched
  artifacts_added: 24
  pass: local-v3

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