Asterisk

1. Open Source: Asterisk is freely available and open-source, allowing for customization and extension according to specific needs.

2. Versatility: It supports various communication protocols such as SIP, H.323, and MGCP, enabling the development of diverse communication solutions.

3. Scalability: Asterisk can scale from small office deployments to carrier-grade systems, making it suitable for businesses of all sizes.

4. Call Routing: It offers flexible call routing capabilities, allowing calls to be routed based on various criteria such as caller ID, time of day, and dialed number.

Before learning Asterisk, it's beneficial to have the following skills:

1. Understanding of Telephony Concepts: Familiarity with telephony concepts such as PBX (Private Branch Exchange), VoIP (Voice over Internet Protocol), SIP (Session Initiation Protocol), and PSTN (Public Switched Telephone Network) will provide a foundation for understanding Asterisk.

2. Linux Command Line: Asterisk typically runs on Linux-based operating systems, so familiarity with basic Linux command-line operations is essential for installation, configuration, and management.

3. Networking Basics: Knowledge of networking fundamentals, including IP addressing, subnetting, routing, and firewall concepts, is necessary for configuring Asterisk to communicate over networks.

4. Scripting and Programming: Basic scripting or programming skills in languages such as Bash, Python, or Perl are helpful for customizing Asterisk configurations and developing additional functionality.

By learning Asterisk, you gain the following skills:

1. Telephony System Administration: You'll learn how to install, configure, and manage Asterisk-based telephony systems, including PBX functionality, call routing, and voicemail.

2. VoIP Protocols and Standards: You'll gain an understanding of VoIP protocols and standards such as SIP, RTP (Real-time Transport Protocol), and SDP (Session Description Protocol) used in Asterisk-based communication solutions.

3. Customization and Scripting: Asterisk offers extensive customization options, allowing you to tailor telephony solutions to specific requirements using scripting languages like Asterisk Dialplan, AGI (Asterisk Gateway Interface), and scripting languages like Perl or Python.

4. Integration with Third-party Systems: You'll learn how to integrate Asterisk with other systems and applications, including CRM software, databases, web services, and other telephony systems, to create comprehensive communication solutions.