I can multitask multiple chats, but I can only focus on one phone conversation at a time. If multiple people are involved on a problem then a bridge is used.
Sometimes I will use chat while on the phone to type out the commands they need to use or to communicate a list of servers. I can also share a monitor screen while talking on the phone.
If the problem is non-trivial, then chat by itself is a pain. I can talk and listen while looking at servers, but if I had to communicate via chat only, it would be a continuous interruption.
The problem with meeting rooms is that it is rare that full attention is needed and I can't do real work at the same time in the meeting room.
If it's social and not work related, I prefer in person.