My method:
Sales guy: ‘Is Mr. XXX there?’
Me: ‘I can get him. Who is calling?’
Sales guy: XXXcompany name
Me: “Hang on, I will get him’
Set phone down and do things, checking periodically, until they hang up, with an occasional ‘hang on! He’s coming!’
This does several things. It keeps that salesman on the line so he isn’t bothering anyone else, so I am helping my fellow human beings.
I also feel good knowing that they are waiting on me. Usually gone in 30 seconds or a minute. Those that wait 5 minutes get. ‘I paged him he must be out in the field. give me a call back number.’