Port :4569IAX2

Inter-Asterisk eXchange version 2 (IAX2) is a communications protocol used for setting up and managing VoIP connections, particularly between Asterisk-based private branch exchanges (PBX). Unlike SIP and RTP, IAX2 consolidates both signaling and media transmission into a single data stream over UDP, which simplifies configurations, especially across NAT devices, and reduces required ports. The encapsulation design results in decreased bandwidth usage, better handling of multiple simultaneous calls via multiplexing, and streamlined firewall management.

Designed with trunking efficiency in mind, IAX2 allows multiple channels to be multiplexed over a single connection. This benefits inter-PBX communications or connections to VoIP service providers by optimizing bandwidth and lowering latency. It supports features such as call authentication, encryption (via extensions and add-ons), voice codecs negotiation, and call control signaling, making it suitable for complex multi-site deployments.

The protocol leverages UDP port 4569 by default, facilitating simpler traversal through firewalls and NAT. Its architecture reduces the number of open ports, which simplifies security management and troubleshooting. IAX2's tight integration with Asterisk systems fuels its adoption in open-source telephony projects and commercial solutions focused on scalable, efficient VoIP implementations.