external machine interface (mobile communications) (EMI)
External Machine Interface (EMI) is the external interface in a GSM paging system between the personalcomputers(PCs) and the Short Message Handler (SMH), which is part of the Short Message Service Center( SMSC). The EMI can be implemented via X.25 connections or via modem or ISDN connections and is based on an extended command set of the Universal Computer Protocol( UCP). This is defined for Ermes paging systems in ETS 300 133-3.