I’ve been looking into different software stacks for building and managing VoIP infrastructure, and I’m curious what people are actually running in production.

There are plenty of options depending on the use case—Kamailio, OpenSIPS, FreeSWITCH, Asterisk, RTPengine, and various commercial platforms. Each seems to have its own strengths once you move beyond a basic lab setup.

For example, Kamailio and OpenSIPS are great for SIP routing and signaling, while FreeSWITCH and Asterisk can handle more application-level voice functionality. RTPengine can also be useful when you need dedicated media handling.

The interesting part is what happens at scale:

• How do you handle high-volume SIP traffic?
• What does your HA/failover architecture look like?
• How do you monitor SIP and RTP performance?
• Are you using containers or traditional servers?
• At what point does commercial software become worth the cost?

I’d be interested to hear what others are using in production and why you chose that stack.

Anyone running a mostly open-source VoIP stack in production? What has worked well—and what would you do differently today