In that days the date of letter delivery and receipt used to be seriously carried out. In front of Hai Phong post office, the tri-coloured flags (French flag) in day time and lights at night were hanged on the days letters were sent. When receiving letters the blue flags bordered with red was hanged in Hai Phong's Post office, while it was flags bordered with blue in Central of the country Post offices. Five minutes after being checked, letters were given to postmen. Hai phong-Ha Noi inter-provincial telephone was officially set up in 19th April 1906.