You mean does the 80s-based protocol that doesn't even support encryption support voice?

It doesn't support having messages received while you were offline

IRC supports one and one thing only: N-wise chats to connected clients. That and delusional nerds who like to think they're better than everyone else. Huge support for that too.

People who actually have sane standards for their instant messaging use the Matrix decentralized chat protocol when they need non-proprietary coms, or revolt