South Korea confirmed it had received a call from the North at 15:30 local time on Wednesday.
The North Korean leader had earlier said he was open to dialogue with Seoul and to sending a team to the Winter Olympics in the South next month.
The two nations have not held high-level talks since December 2015.
North Korea cut off the communications channel shortly afterwards, refusing to answer calls, according to officials in the South.
A North Korean official announced the hotline's reopening in a televised statement.