supply of electronic l.c. gate telephone system., power supply system with mf battery of 12v / 24v dc ( 12v dc supply shall be connected to the station telephone unit & 24v shall be fed to line circuit ) with maintenance free battery for electronic lc gate telephone system as per specification no. rdso / spn / tc-51 / 2011, rev 3.0 amd.1 or latest including battery charger. [ warranty period: 30 months after the date of delivery ] , slave telephone for electronic lc gate telephone system as per specification no. rdso / spn / tc / 51 / 2011 revision 1.0 or latest. [ warranty period: 30 months after the date of delivery ] , master telephone unit with voice logging facility for electronic lc gate telephone system as per specification no. rdso / spn / tc-51 / 2011 revision 1.0 or latest. [ warranty period: 30 months after the date of delivery ]