'I would hardly call protocols like [SIP]... and [RTP]... "custom".' The meaning of "custom" in this context was to distinguish it from a full TCP or raw UDP.

'I would hardly call protocols like [SIP]... and [RTP]... "custom".' The meaning of "custom" in this context was to distinguish it from a full TCP or raw UDP. Not to imply that there's no standard definitions for VOIP protocols. Quite the contrary in fact. The point being made is that UDP is just a substrate to create other protocols that also need to be designed for a purpose. And just calling all these protocols "UDP" is a mistake. Btw, not to be argue from authority, but to back my words with some context, I'm responsible for at least one such "custom" protocol myself. https://packetzoom.com/blog/ https://packetzoom.com/blog/