[Thaxll]

Because control plane does not handle anything phone related most likely? It's like upgrading Kubernates masters, your API servers still works and are not affected.

AFAIK Erlang code does not handle any network traffic, all of that is done in C/C++.

[dmitriid]

This is the original video in its 90s glory: https://www.youtube.com/watch?v=uKfKtXYLG78

Regardless of where the call is handled, you can't just deploy a new switch in a telecom network, but you still want to upgrade them. This is where you really want hot code loading.

[yetihehe]

Real world usage case - I have a server which handles several thousand telematic devices (telemetry+actuation), split into about 20 different device types. It's small device base so doesn't require multiple servers and we can be really cheap. But requiring to disconnect all devices just to make one small change to one device driver would be painful. Now we can have uptime of over half a year and in that time we had changes/fixes to several drivers. Normally that would require scheduled downtime every week and slow us down considerably.