External Short Messaging Entity (ESME) is a term originally coined by Aldiscon to describe an external application that connects to a Short Message Service Center (SMSC) to engage in the sending and/or receiving of SMS messages.
SME is a term used in many cellular circles to describe a network entity (mobile/cell phone) that can send/receive messages. ESME (pronounced EZ-mee) is essentially one of these but without all the wireless aspects; i.e. it is connected via TCP/IP, X.25 or similar. On SMPP 3.4 protocol specifications ESME refers only to external sources and sinks of short messages as Voice Processing Systems, WAP Proxy Servers or Message Handling computers, and it specifically excludes SMEs which are located within the Mobile Network, i.e., a mobile station (MS).
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