All taxicabs shall have posted, printed or placed on each side of the body of such taxicab in lettering not less than two inches in width the taxicab number and the name and telephone number of the taxicab owner; except that, such taxicab may be operated under an emblem or trade name similarly placed on each side of the body of the taxicab when the true name of the owner has been filed in writing with the Taxicab Administrator.