It is the responsibility of the technician to inform the dispatcher that they will be arriving late to their appointment.  They must notify the dispatcher at least 15 minutes ahead of time.  This gives the dispatcher enough time to then turn around and contact the client.
The dispatcher must inform the client that the technician will be late due to unexpected set back at his current appointment. Let the client know that as soon as the technician leaves his current job, he will call the client to let them know that he is on his way or he must notify the dispatcher and let the dispatcher know to notify the client again.