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My (male) coworker who sits behind me has a female friend who calls his direct line every half hour or so, day in, day out.
Almost every time he answers one of these calls, the caller hangs up instantly. Once or twice a day, though, my coworker will have the phone to his ear for a minute or so, presumably listening to her ranting about something, and his only responses after listening to her for a bit are "[Name], I've gotta go, I'm working," "I'm sorry you're having a bad day," "try to relax and not think about it," "I hope your day gets better," "It's not appropriate for me to be talking right now, this is a business line," etc.
I don't mean to eavesdrop, but the calls are very distracting to me, and presumably to my coworker too. The calls do interfere with work tasks, too - if someone is at his desk talking to him, that never stops him from answering and wasting the time of whoever is standing there waiting for him to get off the phone.
Is it my place to say something to him and/or our supervisor? I tend to keep mum about things that bother me but this has been going on for over a year now (she has never missed a day) and it's getting to the point where it's really annoying me and I feel like I at least have to ask him what the deal is with these calls.