The man, whose identity was not disclosed citing security concerns, was detained at southwest Delhi's Sagarpur area and grilled for hours jointly by police and intelligence agency officials.
A case has been registered in connection with the matter and the man is being interrogated.
So far, it has emerged that he is now unemployed and had a heated argument with his wife before he made the calls yesterday evening.
He is also suspected to be a drug addict.
Yesterday, he had first called up police control room at around 6 PM asking for former Delhi Police Commissioner B S Bassi's phone number and when refused, he threatened to have bombs planted in the city.
Around half an hour later, he called up the police control room again, threatening to blow up the Rashtrapati Bhavan.