If I'm trying to work on something, hitting me in the back of the head with a claw-hammer would be scarcely more disruptive than an unsolicited phone call.
I sometimes hear that a cow-orker is talking to me, but I ignore it on purpose, pretending not to notice. Then they usually figure out they need to attract my attention somehow, so they come over / wave their hands / throw an object at me. I respond politely, but with very visible annoyance. This quickly trains them to use IM instead. IM, for which I often have notifications turned off.
Avoiding distractions at workplace is a hard work in itself.
The shared office concept was a mistake inspired by assembly lines. Sharing space with coworkers is good in factories because work is often dull and workers can talk to each other. For creative work, it's nothing but a hindrance.
My knowledge about this comes from a befriended work-psychologist who worked with both, offices and factories, since the 70ies.
Yes. I really can't abide chat for work. If I have time and need synchronous communication, I make a phone call.
Email forces me to think my communication through, and I can explicitly CC/BCC other people if I feel that they need to read my letter.
PS: I find it telling that the product is actually called "Slack". ;)