The unidentified man dropped the phone at the East 105th Street station just before 10 a.m. Tuesday morning.
Officials say he climbed down to the tracks to pick it up, and somehow ended up under the train.
Part of the train is believed to have run over the man. But the man crawled out from under the subway car, got back onto the platform and walked out of the station.
Subway officials say they confirmed the account with workers in the station and would now like to talk to the man.
They also used the incident to stress that commuters should never go onto the tracks to retrieve their dropped items.