Principles of zonal telephone network construction in Ukraine. Numbering in zonal telephone network.
Zonal telephone network contain local telephone network (urban and village) that placed in territory of zone. Whole territory of Ukraine, like every other country, divided to telephone zone. Telephone zone - it is part of country, where all subscribers has the same 7-digits telephone number. Ukraine has 26 telephone zone.
Zonal network present aggregate of TE, that at the same time included in national network and channels.
Each telephone zone has own code, named national code. In Ukraine zonal code are 2 digit and show like BC. Local telephone network inside zone has zonal code. This code is 2 digit, because of number of local network inside zone never more several decade. It shows like ab.
Figure 1.6 – Zonal telephone network
In this way complete national telephone number, dialed by subscriber in case of national call has next form:
0 – ВС – ав – ххххх,
where 0 – index for out zonal call,
In this way complete international telephone number, dialed by subscriber in case of international call will has 12 digits:
+380 – ВС – ав – ххххх.
Prefix codes 0. There are various sublevels. Some are described. Sublevel ‘00’ as a prefix shall be used for international dialling.
The format as per E.164 recommendation is 00 + country code + NSN.
Sublevel ‘0’ as a prefix shall be used for national calls. The format is 0 subscriber number (in national format).
Special services - digit 1 (emergency, services). This level is used for accessing special services like emergency services, supplementary services, inquiry and operator assisted services. The format contains 3 to N digit depending on service.
Principles of urban telephone network construction (utn). Example of utn with five digit numbering construction. Example of analogue-digital utn construction.
Public Switched Telephone Network
Urban Telephone Network – is a complex of station and linear structures, also TS of subscribers to provide telephone services for city’s subscriber.
Simple UTN contains 1 PE.
Correct marking of a PE
Subscriber line (SL) – are necessary for including subscribers into PE. Each SL has own subscriber number. The aggregation of all subscriber number is named numbering.
Numbering capacity – is a maximum possible for one exchange or network quantity of subscriber number.
Zoning UTN (network with a five-digit numbering)
Breaking the whole area of a city into small locations served by PEs is called zoning. Zoning allows to reduce lengths of subscriber lines. The PEs are interconnected with trunks. Trunks between PEs are used more intensively compared to subscriber lines.
A public exchange (PE) provides telecommunication services for subscribers concentrated within a service area of the PE.
The example below shows zoning.
One TE network
A
zoned network
The main reason for zoning is that it reduces costs of subscriber lines. Thus, it saves money.
Another good idea on how to reduce costs of subscriber lines is to use subexchanges.
A subexchange provides telecommunication services for its subscribers.
The example below shows how to connect quasi-electronic subexchange “Kvant” serving 800 subscribers.
Numeration plan of a PE includes numbers of a Subexchange.
Large companies and organizations may use their own switches called Private Branch Exchanges (PBX) to access telephone networks.
The following example shows how to connect a PBX to a PE
Nodal
urban telephone network. UTN-6
If a net contains many PEs then it makes sense to use nodes (called centers) in order to reduce expenses on trunks.
Every NA has its own Host and transit exchange (HTE). It concentrate traffic from PE of own NA and distribute it to other NAs.
All the PEs within a node area are interconnected and access PEs of another node area via HTE.
(scheme
has to be redrowed)
The method shown in the figure allows to make the trunks larger which means they carry more traffic. So they are used efficiently. For example the trunk between PE-22 and HTE-3 carries traffic from PE-22 to PE-31,32, 33.
Traffic towards TEs is conveyed over separate trunks.
Let us look at the same net having 7 PEs. There are trunk groups of toll trunks between a Toll Exchange (TE).