Freeswitch

1. Open-Source: FreeSWITCH is freely available and open-source, allowing for flexibility and customization.
2. Scalability: It offers a scalable architecture suitable for both small deployments and large-scale enterprise applications.
3. Modularity: FreeSWITCH is designed with a modular architecture, making it easy to extend and customize functionalities.
4. Cross-Platform Compatibility: It supports multiple operating systems, including Linux, Windows, and macOS.

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

1. Telephony Fundamentals: Understanding of basic telephony concepts such as SIP, VoIP, and PSTN.
2. Linux Proficiency: Familiarity with Linux operating system commands and administration.
3. Networking Basics: Knowledge of TCP/IP networking protocols and configurations.
4. Scripting or Programming: Basic understanding of scripting languages like Python or programming languages such as C.

By learning FreeSWITCH, you gain the following skills:

1. Telephony System Management: Ability to set up, configure, and manage telephony systems using FreeSWITCH.
2. VoIP Protocol Knowledge: Understanding of VoIP protocols such as SIP, RTP, and WebRTC.
3. Call Routing and Handling: Skills in routing and handling incoming and outgoing calls efficiently.
4. Media Processing: Proficiency in handling voice and video media streams, including transcoding and mixing.