The following words and terms, when used in this chapter, have the following meanings, unless the context clearly indicates otherwise: Applicant -- A person, association, partnership, corporation or government agency making a written or oral request for the commencement of or changes in its public utility service. Application -- A written or oral request to a public utility for the commencement of or changes in public utility service. Automatic dialing-announcing device -- Automatic equipment used for solicitation which has a storage capability of multiple numbers to be called or a random or sequential number generator that produces numbers to be called and has the capability, working alone or in conjunction with other equipment, of disseminating a prerecorded message to the number called. Busy hour -- The continuous 1-hour period of the day during which the volume of traffic is greater than during another continuous 1-hour period of the same day. Busy season -- The calendar month or 30-day period of the year during which the greatest volume of traffic is handled in the office. Calls -- A customer telephone message attempted. Central office -- An operating unit equipped with switching apparatus by means of which telephonic communication is established between telephones connected to it or by the additional aid of trunk lines between the telephones and telephones connected to other central offices. Customer -- A person, association, partnership, corporation or government agency provided with telephone service by a regulated public utility. Exchange -- A unit established by a public utility for the administration of communication services under its specific local exchange service tariff provisions consisting of one or more central offices with associated plant facilities used in furnishing services and having one point designated for the purpose of rating toll calls for customers. Interexchange carrier -- A carrier which provides interexchange telephone services to the public under 66 Pa.C.S. § 3008 (relating to interexchange telecommunication carrier). Local service area -- The area within which customers may call without assessment of toll charges. Message -- A completed customer or user call. Message unit -- A unit of measurement used for a form of exchange service under which originated messages are measured and charged for in accordance with the local exchange tariff. Metering -- The metering of data concerning a customer's calls which is used in preparation of the customer's bill for service which is made by operators, automatic message accounting, message registers or other acceptable data recorder methods. Nonprimary service order -- An application for simple residential or business, voice grade, public utility service which is not primary service. Primary service order -- An application for simple residential or business, voice grade, public utility service to be provided at a customer location which does not have public utility service including, but not limited to, the initial connection of a new customer or the transfer of public utility service of an existing customer's service to a new location. Public utility -- A person or corporation owning or operating equipment or facilities in this Commonwealth for conveying or transmitting messages or communications over the telecommunications network for the public for compensation. The term does not include either a person or corporation not otherwise a public utility who or which furnishes service only to himself or itself or a bona fide cooperative association which furnishes services only to its stockholders or members on a nonprofit basis. Subscriber -- A person, firm or corporation designated on public utility records as the party responsible for payment of bills for telephone service. Surveillance level -- A measurement of telephone service which indicates a need for the public utility to investigate the cause of the problem, to remedy the problem and to inform the Commission of the problem. Trouble report -- A written or oral report delivered to an authorized public utility representative by a customer or user of public utility services which relates to a defect, difficulty or dissatisfaction with the public utility's regulated service. Trunk -- A communication channel between central offices, switching units or private branch exchanges. Working day -- A day except Saturday, Sunday or legal holiday.