Answers

2015-06-19T20:38:17+05:30
ISD:International Subscriber dialling
PCO:Public Call Operator
STD:Subscriber Trunk Dialling

0
2015-06-20T00:16:51+05:30
ISD:International Subscriber dialling 
PCO:Public Call Operator 
STD:Subscriber Trunk Dialling 



these are all related to telephone service

0