The North had threatened to cut off the hotline on March 11 if the United States and South Korea did not abandon their joint military exercise.
The Red Cross hotline is used to communicate between Seoul and Pyongyang which do not have diplomatic relations.
"We called at 9am and there was no response," a government official from South Korea said. The line is tested each day.
Pyongyang has also threatened to cut off a hotline with UN forces in South Korea, at the border "truce village" of Pammunjom.
Tensions on the Korean peninsula have risen since the North conducted a third nuclear test on February 12, prompting new UN sanctions.
South Korea and US forces are conducting large-scale military drills until the end of April, while the North is also gearing up for a massive state-wide military exercise.
North Korea has accused the United States of using the military drills in South Korea as a launch pad for a nuclear war and has threatened to scrap the armistice with Washington that ended hostilities in the 1950-53 Korean War.
The North has threatened a nuclear strike on the United States, but such a threat has been dismissed as rhetoric by analysts, as the North does not have the military capacity to reach the United States.
The North is viewed as more likely to stage some kind of attack along a disputed sea border, if it does anything at all, rather than risk a war with South Korea and the United States, which it would lose, according to most military assessments.
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Cos North Korea is best Korea #insertAsianAccent