At my workplace we use Skype for Business. I often get "IM?" or "OK to IM?"

Starting the conversation that way requires me to greet them and request that they continue.

Why ask if it's OK to IM, if you're using an IM to do it? Ostensibly it's to prevent, like, notification sounds going off from my laptop if I'm in a meeting, or to avoid disrupting me while I work... but sending the "Permission to communicate?" message is already a disruption.

Also, S4B has available/away/busy/meeting/call status indicators. Why not use those if you can't decide if it's OK to IM?