The successful Proposer shall be responsible for every wrecker operator to answer any call made by the City (Azle Police Department or any authorized local authority) on a twenty-four (24) hour basis, seven (7) days a week. Every call for the contracted wrecker service shall be responded to (i.e. the wrecker arriving on scene) within twenty (20) minutes on a consistent basis. Such notification is to be rendered to the successful Proposer at a single telephone number to be designated by the successful Proposer. The police dispatcher will log on the call and wrecker log when contact is made, or attempted to be made with the wrecker, and when the wrecker is en route. Exceptions may be made to this requirement if unforeseen or extenuating circumstances are involved in the judgment of the Chief of Police or his designee.