It's impolite to use someone's phone without permission.
Linda is at work beside her coworker's desk when she realizes she has to tell her husband Hank to pick up her mediciine.
Linda wants to locate a telephone and use it to call Jim.
Linda goes over to her own desk and locates her own desk phone and uses it to dial Hank.
Linda looks over at the nearest desk and sees a coworker's cellphone which she grabs and makes a quick call.
Linda's coworker continues to work uninterrupted and finishes her work.
The coworker is furious that Linda had the audacity to just take her phone and use it.