Approach anxiety is a real issue among many people in the world. This kind of anxiety is triggered whenever someone approaches you for whatever reason. Whether it is a person walking towards you, or your colleague/boss giving you a call on the phone. Approach anxiety is more or less, a manifestation of the social fears that we have.
If for instance, I fear that I’m about to lose my job, then receiving a missed call from my boss would put me in a state of restlessness. To overcome approach fear, one needs to get some psychological counseling as that helps a lot!