It depends on what your company does. If someone comes to talk business with your company, they won't have any opinions. If your company finds someone else to do business, I don't think it is necessary. There are recording tips, which will make people feel nervous, afraid that you will catch his pigtails with recording in the future. Moreover, the recording is only kept by your company, and he doesn't, which will cause a psychological disadvantage to the guests. When I received a call with this tone, I just answered it casually and hung up.