What is FreeSWITCH and how is it different from Asterisk? +

FreeSWITCH and Asterisk are both open-source telephony frameworks that handle SIP calls, IVR, call routing and media processing without any licence cost. The fundamental architectural difference is how they handle concurrency. Asterisk uses a thread-per-call model: each active call consumes a dedicated thread, which limits practical concurrency to a few hundred simultaneous calls on a typical server before memory and CPU contention becomes significant. FreeSWITCH uses an event-driven, asynchronous core: calls are handled as events on a shared thread pool, allowing a single FreeSWITCH node to sustain thousands of concurrent sessions on the same hardware. For Indian businesses with fewer than 200–300 concurrent calls, both platforms are equally capable and Asterisk's larger Indian developer community makes it easier to find support. Above 500 concurrent sessions, FreeSWITCH's architectural advantage becomes operationally significant. Indian CPaaS providers, OBD platform builders, large BPOs and telecom resellers choose FreeSWITCH specifically for this reason.