MCEF stands for Mobile-Station-Memory-Capacity-Exceeded-Flag. It is a flag that indicates whether the memory capacity of the mobile station has been exceeded or not. It is used in the context of the Short Message Service (SMS) of the GSM cellular system.
The significance of MCEF is that it allows the Service Centre (SC) to decide whether to send more messages to the mobile station or not. If the MCEF is set to 1, it means that the mobile station cannot store any more messages, and the SC should stop sending messages until the mobile station clears some space or requests more messages. If the MCEF is set to 0, it means that the mobile station has enough memory capacity to receive more messages, and the SC can continue sending messages as normal.
MCEF is one of the options that can be specified in the TP-User-Data-Header-Indicator (TP-UDHI) field of the SMS Transfer Protocol Data Unit (TPDU). The TP-UDHI field is used to indicate the presence of a header in the user data field of the TPDU, which can contain additional information or parameters for the SMS. MCEF is one of the possible parameters that can be included in the header.
MCEF is an example of how cellular communications can optimize the use of resources and provide better services to the users. By using MCEF, the SC can avoid wasting bandwidth and battery power by sending messages that the mobile station cannot store or read. The mobile station can also control the flow of messages and avoid being overwhelmed by too many messages. MCEF is a simple but effective way to improve the efficiency and reliability of SMS.