One of The Oldest Passenger Train of Northeast Frontier Railway 15703 / 04 New Jalpaiguri - Bongaigaon Express is an Express train belonging to Indian Railways Northeast Frontier Railway zone that runs between New Jalpaiguri Junction of Siliguri, West Bengal and Bongaigaon of Assam in India. It operates as train number 15703 from New Jalpaiguri Junction to Bongaigaon and as train number 15704 in the reverse direction serving the state of West Bengal and Assam.