V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

EMI
       ElectroMagnetic Interference


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

EMI
       External Machine Interface [protocol] (SMS)


The Free On-line Dictionary of Computing (30 December 2018):

External Machine Interface
EMI

    (EMI) A protocol primarily used to connect to
   short message service centres for mobile telephones.  EMI
   is an extension to Universal Computer Protocol (UCP).  EMI was
   was developed by CMG, now a part of LogicaCMG, the current
   SMSC market leader.

   Each byte of the message is encoded as two hexadecimal
   characters using an encoding not quite like ASCII.

   EMI specification
   (http://www.netfunitalia.it/downloads/SMSC_EMI_Specification.PDF)

   (2007-09-10)