A method is disclosed for operating a cellular communications system of a type that comprises a Base Station/Mobile Switching Center/Internetworking function (BMI) and a plurality of mobile stations. The method includes the steps of transmitting a point-to-multipoint message (e.g., a Broadcast SMS message) from the BMI to the plurality of mobile stations; and, in at least some of the plurality of mobile stations, receiving the point-to-multipoint message and transmitting an acknowledgement to the BMI using a point-to-point message. The point-to-multipoint message includes an information element having a value for specifying one of (a) that a mobile station receiving the message is prohibited from responding to the message, (b) that a mobile station receiving the message must respond to the message, and (c) that a mobile station receiving the message may optionally respond to the message. Mobile stations receiving the message selectively respond or not respond to the message, at least as a function of the value of the information element.