At the company where I used to work, there was an expectation that a dispatcher would make a quick call to the customer when a technician was on the way to the customer’s home. This call was usually placed between five and 45 minutes before the technician’s arrival time, depending on how close the tech was to hitting the time window we had promised the customer.
Our dispatcher would do a little dance, hoping that the technician would end at least two minutes before the window for the next customer had expired, so we could at least give them their “heads-up call” within the time window we had quoted them, as if this were some sort of saving grace for the dispatcher. As if this would appease the frustration that the customer was feeling while they were sitting on their couch, second cup of coffee in hand, getting more and more upset as each minute passed.