http://www.mtp.indianrailways.gov.in/uploads/files/1413262648733-STM Topology.jpg Topology.jpg
Optical Fibre Cable Communication System
1)One combine link of STM-1 & STM-4 have been installed for the section from Noapara to Kavi Subhash of Metro Railway for providing backbone support to all telephone, signalling, SCADA and other circuit Via 2 Mb/s.
2)One 8 Mb/s link has been installed for the old section from KDMI to KMUK for providing telephone. But at new section telephone has been provided through 2Mb/s.from Netaji to Shahid Khudiram. Kavi Subhash station telephones have been provided from local KKVS Exchange.
3)Three nos. Optical Fibre Cable has been laid Via UP & DN line in Old Section from KDMI to KMUK tunnel, and one no. Optical Fibre Cable has been laid Via UP line in new section from KMUK to KKVS.