Extended short message entity is an external application that is interconnected to Short Message Service Centre (SMSC) using CIMD/SMPP protocols. In the field of telecommunication the main function of this interconnection is to allow the transfer of messages between ESME and Mobile Stations (SM). The CIMD/SMPP protocols receive support from the two distinct message centers, namely Short Message Service Center (SMS Center) and Unstructured Supplementary Data Center.
When SMS Center receives a message from application, it uses standard retry policy to deliver the message on its own. If there is a failure in message delivery, the particular message will get stored in the SMS Center Database until the delivery is successfully completed. The message will get deleted in the event of permanent error or the expiry of message’s validity period. Computer interface supports TCP/IP sockets, X.25 PAD, serial ports (modems) and is perfectly compatible with client applications that send and retrieve messages.