Saying obscene things on the telephone is illegal.

Sec. 8-136. Telephone communications, improper language, harassment. (a) No person shall: (1) Engage in or institute a telephone call, telephone conversation, or telephone conference, with another person, anonymously or otherwise, and therein use obscene, profane, vulgar, lewd, lascivious, or indecent language, or make any suggestion or proposal of an obscene nature or threaten any illegal…