N.Y.C. Admin. Code § 19-507.3: § 19-507.3 Reporting requirements.

a. An owner shall maintain on file with the commission a current telephone number serviced by an answering machine or recording device, a pager number, telephone answering service number or other information by which telephone contact with the owner or a designated representative may reasonably be expected to be made at all times. An owner or designated representative must respond to any telephone or pager contact from the commission within forty-eight hours.