It is unlawful for any peddler or solicitor or any person pretending to be a peddler or solicitor to ring the bell or knock at any building whereon there is printed or affixed or otherwise displayed to public view any sign containing any or all of the following words: "No Peddlers," "No Solicitors" or "No Agents," or which otherwise purports to prohibit peddling or soliciting on such premises. (Ord. 377 NCS §10; prior code §20.2.)