Question

PSTN , BSNL , MTNL , VSNL and SCSI stand for ?

Answer 1

PSTN - PUBLIC SWITCHED TELEPHONE NETWORK 
BSNL -BHARAT SANCHAR NIGAM LIMITED 
MTNL - MAHANAGAR  TELEPHONE  NIGAM LIMITED 
SCSI - SMALL COMPUTER SYSTEM INTERFACE CODE 
VSNL- VERY LARGE SCALE INTEGRATION

Answer 2

PSTN stands for Public Switched Telephone Network

BSNL stands for Bharat Sanchar Nigam Limited 

MTNL stands for Mahanagar Telephone Nigam Limited

VSNL stands for Videsh Sanchar Nigam Limited

SCSI stands for Small Computer System Interface