Provided are an artificial intelligence system for simulating functions and so forth of human brains by using a mechanical learning algorithm. A method, performed by a device, of providing a notification message about a call request may include one or more of receiving the call request from another device, obtaining context information about a situation of a user if a user input accepting the call request is not received within a preset time, determining a reason for a non-response of the user by analyzing the context information, obtaining information about a relationship between the user and another user of the other device, generating a notification message describing the reason for the non-response based on the context information, determining whether to transmit the notification message to the other device based on the reason for the non-response and the information about the relationship, and transmitting the notification message to the other device based on the determination.