1.  A certificate holder shall have each taxicab equipped with a mobile radio and shall maintain central facilities for dispatching taxicabs at all times. The facilities:

(a) May be maintained individually or in cooperation with other certificate holders.

(b) Must be principally engaged in communication by radio with the taxicabs of the certificate holder or holders.

2.  As used in this section, ‘communication by radio’ means the transmission of writing, signs, signals, pictures, and sounds of all kinds by radio or other wireless methods, including all facilities and services incidental to such transmission, which facilities and services include, without limitation, the receipt, forwarding and delivering of communications.