Std Full Form Telephone 6: ISD full form PCO full

Std Full Form Telephone 6 ISD full form PCO full form Where are these STD full form is Subscriber Trunk Dialling ISD full form is International Subscriber Dialling PCO full form is Public Call Office The terms STD ISD PCO Std full form telephone Brainlyin Subscriber trunk dialling STD also known as subscriber toll dialing.