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Programmable voice calling infra for developers
The voice platform for business teams and developers. Automated calling workflows for your team. Programmable voice infrastructure for your applications.
THE PROBLEM
Why legacy telecom infrastructure fails Al-to-human conversations
Regional data residency
Standard PSTN and SIP routing add delay that breaks conversational flow. When round-trip time exceeds a few hundred milliseconds, the AI and user end up talking over each other.
No Raw Audio Access
Most CPaaS providers don’t offer low-level access to raw media streams. Without it, developers can’t implement custom Voice Activity Detection or reduce AI processing lag.
Human-First Architecture
Legacy stacks are built for human-to-human sessions. They lack the hooks needed for instant interruption handling, dynamic media injection, and millisecond-perfect state changes.
Infrastructure Management Overhead
Managing carriers, SIP trunks, and global telephony routing distracts product teams. Developers spend more time on telecom plumbing than on optimising the actual AI model and user experience.
PLATFORM FEATURES
Programmable voice infrastructure and real- time audio streaming at scale
Choose the approach that fits your architecture. Both support global numbers, transparent debugging, and programmable call control.
Voice Apps
Real-time audio streaming via WebSocket. Stream audio between phone calls and your application in real-time.
SIP Trunking
Enterprise-grade and programmable SIP infrastructure. Connect your existing SIP-enabled platforms directly to our carrier network.
CORE INFRASTRUCTURE
Everything you need to ship AI-enabled voice features
Real-time Media Streaming
Real-time, bidirectional audio streaming between phone calls and your server.
Global Phone Numbers
Power through candidate lists with progressive dialing. Move from one screening to the next, with automated voicemail drops when they don’t pick.
SIP Trunking
Programmable Call Control
Call Recording & Analytics
How it Works
FreJun Teler streams live call audio to your AI backend via WebSocket, enabling real-time processing and seamless AI-generated responses during the conversation.
Connection & Webhook Trigger
When a call hits your FreJun Teler number, we instantly send a webhook to your application server with all necessary session metadata.
Bidirectional WebSocket Establishment
Your server opens a full-duplex WebSocket, and FreJun begins streaming raw audio frames (L16/8000Hz) from the caller to your endpoint with sub-250ms latency.
Real-Time AI Orchestration
Your backend pipes the audio through your AI stack (STT → LLM → TTS) and streams the synthesized response back through the open socket.
Low-Latency Media Injection
FreJun Teler receives the AI’s audio stream and injects it into the live call. Our platform handles the complex jitter buffering and synchronization required to ensure the conversation remains fluid and natural.
USE CASES
What developers build
with FreJun Teler
Al Voice Agents
Connect phone calls to your AI models via real-time audio streaming. Build schedulers, support agents, etc. with AI-to-human handoffs.
Intelligent IVR
Build multi-level IVR flows with keypress-based menus. Route callers to the right team based on their input for faster resolution.
Customer Support
Voice-enabled support systems that handle queries, access customer data, troubleshoot issues, and escalate to humans when needed.
Outbound Campaigns
Programmatically initiate outbound calls for lead qualification, outreach, or appointment booking. Build logic that adapts based on responses.
Voice-Enabled SaaS
Add click-to-call, call recording, transcription, or voice features directly into your product. Embed telephony without building infrastructure.
Certified Security Frameworks for Reliable Voice AI
SOC2 Type 2 Certified
ISO 27001 Certified
GDPR Compliant
WHY TELER
Beyond generic CPaaS. Beyond raw SIP trunking
Purpose-Built for AI Interaction
Unlike general-purpose CPaaS platforms designed for broad use cases like SMS and IVRs, Teler is optimized specifically to simplify the developer experience of real-time voice and media coordination.
Simplified Integration Logic
Teler abstracts the complexity of managing live audio streams and response coordination, allowing your team to connect phone calls directly to automation workflows without needing deep telecom expertise.
Conversation-First Engineering
By providing a bridge for real-time audio streaming between callers and your application, Teler lets you focus on conversation intelligence and model quality rather than media handling.
High-Performance Abstraction
Teler provides the performance of SIP trunking while eliminating the engineering burden of managing media negotiation, scaling, and carrier reliability through a ready-to-use application interface.
Works with your
favorite tools
FreJun connects natively with Salesforce, HubSpot, Zoho, Freshworks and other CRMs, ATS platforms, and helpdesks. Two-way sync keeps your data accurate across every tool your team already uses.
What is FreJun Teler?
FreJun Teler is a programmable voice API and telephony infrastructure for developers building AI phone agents, real-time voice applications, and custom voice workflows. FreJun Teler handles carriers, audio streaming, and call control so you can focus on your product.
How does real-time media streaming work in FreJun Teler?
FreJun Teler streams audio between live phone calls and your application in real time via WebSocket, with sub-250ms latency. You receive caller audio as it happens, process it with any AI provider, and stream responses back instantly.
What is the difference between Voice Apps and SIP trunking in FreJun Teler?
Voice Apps give you direct WebSocket-based calling with full audio access for custom AI voice automation. SIP trunking connects your existing voice platforms or AI providers via standard SIP protocol, FreJun Teler handles media streaming and carrier complexity on both.
Which AI providers can I connect to FreJun Teler?
FreJun Teler is model-agnostic. Connect ElevenLabs, Vapi, Retell, Livekit, OpenAI, Anthropic, Deepgram, or any custom model via real-time voice streaming infrastructure. There is no lock-in and you pay your AI provider directly.
Does FreJun Teler provide a voice SDK?
Yes. FreJun Teler offers SDKs and a Conversations API for embedding real-time communications and telephony infrastructure directly into your application.
What are channels in FreJun Teler?
Channels are the number of simultaneous calls your account can handle across Voice Apps or SIP trunks. They are shared across your account and can be configured via the channel limit attribute. More channels means more concurrency.
Can I test FreJun Teler without a credit card?
Yes. FreJun Teler provides prototyping credits so developers can test and build without a credit card.
What uptime does FreJun Teler guarantee?
Contact the FreJun team for specific SLA details based on your plan.
Get started with FreJun today
Everything your team needs to call, log, and analyse every conversation, set up and running in hours.