History
3rd Field Signal Coy first appeared in 1940 as a PDF unit in the Curragh Command. In 1942 it becamae a unit of the 3rd Bde in I Division in the Southern Command. in 1946 it was disbanded.
As a result of the re-org in 1959 the 3rd Field Signals Coy was re-established as a reserve unit of An Forsa Cosanta Aituil (FCA) based in Sarsfield Bks in Limerick.
In 1998 the name changed to 3rd Field CIS Coy with the merger of the Signals Corps and Military Information Systems.
In 2005 the name changed to 31st Reserve CIS Coy.
In 2013 the reorganisation of the Reserve Defence Forces resulted in the disestablishment of the 31st Reserve CIS Coy with the remaining members transferring into the reserve platoon of the 28th Inf Bn ending over 72 years of having a reserve comms unit in the Western Command/Bde which itself was disestablished.