Ответь на вопросы по тексту:
True, false or no information? Find the sentences in the text that support 
your point of view.
1) Telecommunications network nodes are connected via transmission links.
2) A public switched telephone network or PSTN is a radio network distributed over land areas.
3) A cellular network consists of telephone lines, fiber optic cables and
undersea telephone cables.
4) The first global network was established using electrical telegraphy.
5) The GSM mobile communication network is used by over 6 billion 
people worldwide.
6) In a mobile network a large number of portable phones communicate 
with each other via base stations.
7) The PSTN includes now different networks.
A telecommunications network is a collection of terminal nodes, links and 
any intermediate nodes which are connected so as to enable telecommunication between the terminals. The transmission links connect the nodes together. The nodes use circuit switching, message switching or packet switching to pass the signal through the correct links and nodes to reach the correct destination terminal. Each terminal in the network usually has a unique address, so messages or connections can be routed to the correct recipients. The collection of addresses in the network is called the address space. Examples of telecommunications networks are: 
 computer networks;
 the telephone network;
 the global Telex network.
A telephone network is a telecommunications network used for telephone 
calls between two or more parties. There are a number of different types of telephone network. A landline network where the telephones must be directly wired into a single telephone exchange. This is known as the public switched telephone network or PSTN. A private network where a closed group of telephones are connected primarily to each other and use a gateway to reach the outside world. This is usually used inside companies and call centers and is called a private branch exchange (PBX).
A wireless network where the telephones are mobile and can move 
around anywhere within the coverage area. Public telephone operators (PTOs) own and build networks of the first two types and provide services to the public under license from the national government. Virtual Network Operators (VNOs) lease capacity wholesale from the PTOs and sell on telephony service to the public directly. The public switched telephone network (PSTN) is the aggregate of the world’s circuit-switched telephone networks that are operated by national, regional, or local telephony operators, providing infrastructure and services for public telecommunication. The PSTN consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all interconnected by switching 
centers, thus allowing any telephone in the world to communicate with any other. Originally a network of fixed-line analog telephone systems, the PSTN is now almost entirely digital in its core network and includes mobile and other networks, as well as fixed telephones. The technical operation of the PSTN adheres to the standards created by the ITU-T. These standards allow different networks in different countries to interconnect seamlessly. The E.163 and E.164 standards provide a single global address space for telephone numbers. The combination of the interconnected networks and the single numbering plan make it possible for any phone in the world to dial any other phone. A cellular network or mobile network is a radio network distributed over land areas called cells, each served by at least one fixed-location transceiver, known as a cell site or base station. In a cellular network, each cell characteristically uses a different set of radio frequencies from all their immediate neighboring cells to avoid any interference. When joined together these cells provide radio coverage over a wide geographic area. This enables a large number of portable transceivers (e. g., mobile phones) to communicate with each other and 
with fixed transceivers and telephones anywhere in the network, via base 
stations, even if some of the transceivers are moving through more than one cell during transmission. Although originally intended for cell phones, with the development of smartphones, cellular telephone networks routinely carry data in addition to telephone conversations.
A wireless network is any type of computer network that uses wireless 
data connections for connecting network nodes. Wireless networking is a method by which homes, telecommunications networks and enterprise (business) installations avoid the costly process of introducing cables into a building, or as a connection between various equipment locations. Wireless telecommunications networks are generally implemented and administered using radio communication. This implementation takes place at the physical level (layer) of the OSI model network structure. Examples of wireless networks include cell phone networks, Wi-Fi local networks and terrestrial microwave networks. Global System for Mobile Communications (GSM) network is divided into three major systems: the switching system, the base station system, and the operation and support system. The cell phone connects to the base system station which then connects to the operation and support station; it then connects to the switching station where the call is transferred to where it needs to go. GSM is the most common standard and is used for a majority of cell phones.