Out of the total of 3,670 towers, 2,537 are installed illegaly while only the rest 1,133 have legal sanction.
SDMC has four zones - South, Central, West and Najafgarh - and maximum number of illegal towers have been found in Central Zone (1,108), the SDMC said.
The corporation, however, has decided to take action such illegal towers and necessary directions have been issued to all zonal offices.
The SDMC is also exploring possibilty of utilising other municipal buildings for installation of cell towers on their roof tops.