It shall be unlawful for any person, either an owner, agent, or otherwise, to operate, conduct, advertise, or otherwise engage in or profess to be engaged in the business or service of the transportation of emergency medical patients upon the streets, or any public way or place, in the incorporated territory of the City of Sebastopol without possessing a valid permit to do so issued pursuant to Section 28 of the Sonoma County Code and has entered into a written agreement for ambulance service within the City of Sebastopol. Upon compliance with the foregoing, certificate of public convenience and necessity under Ordinance No. 411 of the City of Sebastopol shall not be required.