23b) multiplex operator – an entity which: a) obtained a general exclusive frequency licence in a broadcasting service for the broadcasting or re-broadcasting of television or radio programmes in a digital terrestrial way within the multiplex and b) performs telecommunications activities and has its own telecommunications infrastructure or concluded an agreement for the provision of multiplex signal transmission service with a broadcasting network's operator; 23c) broadcasting network's operator – a telecommunications undertaking providing terrestrial broadcasting signal transmission services; 24) (deleted); 24a) call – physical or logical connection of telecommunications terminal equipment allowing for transfer of telecommunications messages; 25) network interconnection – physical and logical connection of public telecommunications networks used by the same or different telecommunications undertakings in order to allow users of services or networks of one telecommunications undertaking to communicate with the users of services or networks of the same or another telecommunications undertaking, or to access services provided by another telecommunications undertaking; network interconnection is a specific kind of telecommunications access implemented between operators; 26) telephone call – a call established by means of a publicly available telecommunications service, supporting two-way voice communications; 27) telecommunications undertaking – an undertaking or another entity authorised to pursue business activities under separate provisions and which conducts business activities consisting in the provision of telecommunications networks, associated facilities or in the provision of telecommunications services, whereby the telecommunications undertaking authorised to provide: a) telecommunications services shall be referred to as a “service provider”, b) public telecommunications networks or associated facilities shall be referred to as an “operator”; 27a) telecommunications message – contents of telephone calls and other information transmitted by means of telecommunications networks; 27b) telecommunications connection: a) a section of an underground cable line, an overhead cable line or a cable duct, contained between a branch connector and a termination point of these lines or ducts within a building facility, b) a wireless system connecting an internal installation of a building facility with a node in the public telecommunications network – enabling the use of publicly available telecommunications services within a building facility; 28) (deleted); 29) public telecommunications network – a telecommunications network used mainly for the provision of publicly available telecommunications services; 30) publicly available telephone service – a telecommunications service made available to the public for originating and receiving, directly or indirectly, national or national and international telephone calls through a number or numbers in a national or international telephone numbering plan; 31) publicly available telecommunications service – a telecommunications service available to the general public; 32) regulatory accounting – a particular kind of accounting in relation to accounting under the provisions of the Accounting Act of 29 September 1994 (Journal of Laws of 2016, items 1047