> ## Documentation Index
> Fetch the complete documentation index at: https://docs.freyavoice.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Telephony Overview

> Understanding telephony systems, call handling, and voice infrastructure in Freyavoice AI

## Telephony in Freyavoice AI

Telephony is the foundation that enables your AI agents and workflows to interact with the real world through phone calls. Understanding how telephony works in Freyavoice AI helps you build more reliable and effective voice AI applications.

## Telephony Architecture

### SIP-Based Infrastructure

Freyavoice AI uses Session Initiation Protocol (SIP) for call handling, which is the industry standard for voice over IP (VoIP) communications. This enables:

**Reliable Call Handling**: Robust call setup, management, and teardown.

**Quality Audio**: High-quality audio transmission with support for various codecs.

**Scalability**: Handle high call volumes with distributed infrastructure.

**Provider Flexibility**: Work with multiple telephony providers and SIP trunks.

### Call Flow

When a call is initiated or received:

1. **Call Signaling**: SIP messages establish the call session
2. **Media Negotiation**: Audio codecs and parameters are negotiated
3. **Media Streaming**: Audio streams bidirectionally between caller and agent
4. **Call Control**: Call state is managed throughout the conversation
5. **Call Termination**: Call is properly terminated and resources are released

## Phone Number Management

### Number Types

**Local Numbers**: Numbers with specific area codes for local presence.

**Toll-Free Numbers**: 800, 888, 877 numbers for nationwide calling.

**International Numbers**: Numbers from various countries for global reach.

**Vanity Numbers**: Memorable numbers with specific patterns (e.g., 1-800-FLOWERS).

### Number Capabilities

**Voice**: Make and receive voice calls.

**SMS**: Send and receive text messages.

**MMS**: Send and receive multimedia messages (if supported).

**Fax**: Send and receive faxes (if supported).

## Call Routing

### Inbound Routing

**Number Resolution**: When a call comes in, Freyavoice AI identifies which agent or workflow to use based on the phone number configuration.

**Session Creation**: A unique call session is created with identifiers for tracking.

**Agent/Workflow Activation**: The configured agent or workflow is activated to handle the call.

**Call Processing**: The agent/workflow processes the conversation in real-time.

### Outbound Routing

**Call Initiation**: Your application or campaign initiates an outbound call.

**Number Selection**: Freyavoice AI selects the appropriate phone number for the call.

**Destination Dialing**: The destination number is dialed.

**Connection**: Once connected, the agent/workflow takes over.

**Processing**: Same as inbound calls from this point forward.

## Audio Processing

### Codecs

**G.711**: Standard codec for high-quality audio, commonly used in telephony.

**G.722**: Wideband codec for better audio quality.

**Opus**: Modern codec with excellent quality and efficiency.

**Codec Selection**: Codecs are automatically selected based on network conditions and provider support.

### Audio Quality

**Network Optimization**: Audio is optimized for various network conditions.

**Echo Cancellation**: Built-in echo cancellation for better call quality.

**Noise Reduction**: Noise reduction algorithms improve audio clarity.

**Adaptive Bitrate**: Bitrate adapts to network conditions for optimal quality.

## Provider Integration

### Twilio Integration

**Primary Provider**: Twilio is the primary telephony provider for Freyavoice AI.

**Number Import**: Import existing Twilio numbers into Freya.

**Call Handling**: Twilio handles call routing and media streaming.

**SMS/MMS**: Twilio provides SMS and MMS capabilities.

### Other Providers

**SIP Trunks**: Connect to other SIP providers for additional flexibility.

**Provider Redundancy**: Multiple providers ensure reliability and failover.

**Regional Providers**: Use regional providers for better local presence and costs.

## Call Quality and Reliability

### Quality Metrics

**Audio Quality**: Monitor audio quality metrics like MOS (Mean Opinion Score).

**Latency**: Track call latency to ensure real-time conversation feel.

**Packet Loss**: Monitor packet loss which can degrade audio quality.

**Jitter**: Track jitter which can cause audio artifacts.

### Reliability Features

**Automatic Failover**: Automatic failover to backup providers if primary fails.

**Retry Logic**: Automatic retry for failed calls.

**Health Monitoring**: Continuous monitoring of telephony infrastructure health.

**Redundancy**: Multiple redundant systems ensure high availability.

## Compliance and Regulations

### Telephony Regulations

**TCPA (US)**: Telephone Consumer Protection Act compliance for US calls.

**GDPR (EU)**: General Data Protection Regulation compliance for EU operations.

**Local Regulations**: Compliance with telephony regulations in various countries.

**Do-Not-Call Lists**: Respect and maintain do-not-call lists.

### Best Practices

**Consent Management**: Obtain and track consent before making calls.

**Opt-Out Handling**: Immediately honor opt-out requests.

**Caller ID**: Use proper caller identification.

**Recording Consent**: Obtain consent before recording calls (where required).

## Next Steps

<Card title="Inbound Calls" icon="phone-incoming" href="/guides/telephony/inbound-calls">
  Learn how to handle and optimize inbound call processing.
</Card>