HARRISBURG — Pennsylvanians picked up telephones, surfed websites and sought out information in person Tuesday, the first day to enroll in health insurance under President Barack Obama’s signature health care law, although glitches apparently made enrollment nearly impossible for many.

Telephones at Hamilton Health Center in Harrisburg rang steadily after the center’s phone number was printed in the local newspaper as an outlet for information about the new online health insurance exchange designed for people without insurance.

“Our phones have been ringing off the hook,” said the center’s CEO, Jeannine Peterson. “Primarily, people just want information. ‘We’ve heard that the Affordable Care Act is coming. We’ve heard about the exchange, but what does that mean to the everyday person?”’

Pennsylvania is one of 36 states whose online exchanges are being run by the federal government after Gov. Tom Corbett, an opponent of the health care law, declined to take on the job. All told, 56 plans are available to Pennsylvanians on the insurance exchange.

Coverage begins Jan. 1 and the initial enrollment period continues until March 31.

In Philadelphia, Independence Blue Cross parked an Internet-capable truck with 14 computer work stations at the Rising Sun Health Center in North Philadelphia to distribute information on its 13 plans on the exchange.

The glitches Tuesday on the federal government’s Web portal, healthcare.gov, seemed to prevent many people from signing up, and Independence Blue Cross had scheduled call backs with people who had sought to enroll or, at least, log in to the online exchange.