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

# SIP Trunking Overview

Learn about SIP trunking and how it enhances your communication capabilities. This guide provides an overview of SIP features and benefits.

## What is SIP trunking?

**Session Initiation Protocol (SIP) trunking** lets you make and receive phone calls and other digital communications over the internet. A **trunk** is a virtual phone line that allows calls over the internet to anyone with a phone number.

SIP trunks support voice, video, and messaging, replacing analog and ISDN phone lines. Many countries are phasing out ISDN, making SIP trunking the future of business telephony.

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## Benefits of SIP trunking

SIP trunking is ideal for businesses of all sizes. If you expect increased call volumes, SIP trunking offers:

### 1. Cost savings

* Pay per channel for the number of concurrent calls you need
* Lower setup and call charges, especially for international calls
* Choose between metered and unmetered plans

### 2. Scalability

* Add or remove channels as your business grows
* Free calls between locations using the same carrier
* Adjust bandwidth for more concurrent calls
* Use dedicated data circuits for guaranteed quality

### 3. Reliability

* Automatic number failover and diverse call routing
* Backup internet connections for resilience

### 4. Real-time analytics & insights

* Instant call logs and AI-driven insights
* Detailed user breakdowns for performance tracking

### 5. Centralized communication

* Unify voice, video, and messaging on one platform

### 6. Call quality

* High-quality digital calls with minimal dropouts
* Automatic error correction for clear audio

### 7. Security

* Dedicated, monitored connections with alerts for unusual activity

### 8. Flexibility

* Use local numbers in multiple regions
* Retain phone numbers when relocating

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## How SIP trunking works

SIP trunking replaces ISDN and copper lines by sending digital call packets over data networks.

### SIP channels

* Each channel is like a digital phone line, allowing one inbound and one outbound call at a time
* Add new channels without extra hardware

### SIP trunks

* Group multiple channels (usually 20+)
* Bridge your phone system and your Internet Telephony Service Provider (ITSP)
* Connect PBX systems to the Public Switched Telephone Network (PSTN)

### SIP protocol

* Defines how to start and end internet-based communication
* Supports voice, video, and messaging

### SIP provider

* Offers SIP trunking services and integrates with your PBX or IP PBX

***

SIP trunking is a future-proof solution for cost-efficient, scalable, and feature-rich digital telephony. 💡

* **[Inbound SIP Call](types/inbound-sip-call)**
* **[Outbound SIP Call](types/outbound-sip-call)**