Millions of voters have reportedly received automated calls telling them to "stay safe and stay home".
Americans are voting in one of the most divisive presidential polls in decades, pitting incumbent Republican Donald Trump against Democrat Joe Biden.
The origins of the calls remain unclear, and some have not specifically mentioned voting.
"There's a little bit of confusion about this one across the industry," Giulia Porter, vice president at RoboKiller, a company that fights robocalls, told the Reuters news agency.
