The entire issue of making business-related calls from any location where one may be overheard suggests poor operational security by the business. Any place which does not explicitly prohibit this conduct by its employees deserves to lose its clients / customers and further puts itself at real legal liability risk in the event of a data breach or loss of trade secret information.

There are very few people who have jobs so sensitive that they cannot be out of touch by voice comms for a few hours and those very few people generally fly private aircraft with secure comms for that reason.

It is a sign of poor organization, self-importance and poor client / customer service.