Communication system

This communication system is provided with: an answer phone center; a first portable telephone that registers an answer phone setting in the answer phone center; a second portable telephone with a display unit and an operating unit that makes a call to the first portable telephone; and a telephone communication network that connects the first portable telephone, the second portable telephone, and the answer phone center in a communicable manner. The answer phone center, when it is determined that the second portable telephone made a call to the first portable telephone and that the answer phone setting is implemented, generates an answer phone message attached with a reply program attached with an advertising image based on the answer phone setting, and transmits the answer phone message to the second portable telephone. The second portable telephone, upon reception of the answer phone message, causes the display unit to display an image of the reply program on which the advertising image is superimposed.