PSTN .

• PSTN

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Public switched telephone network - PSTN operators

1 The task of building the networks and selling services to customers fell

to the network operators. The first company to be incorporated to

provide PSTN services was the Bell Telephone Company in the United

States.


Telecommunications in Bangladesh - PSTN

1 Bangladesh Telecommunications Company Limited (former BTTB)-

Now having the largest PSTN subscriber base..


Telecommunications in Bangladesh - PSTN

1 The number of PSTN subscribers in Bangladesh as of February 2009 was 1.372

million.


Voice over IP - PSTN integration

1 The Media VoIP Gateway connects the digital media stream, so as to complete

creating the path for voice as well as data media. It includes the interface for connecting the standard PSTN networks

with the ATM and Inter Protocol networks. The Ethernet interfaces are also included in the modern systems,

which are specially designed to link calls that are passed via the VoIP.



1 Most VoIP implementations support E.164 to allow calls to be routed to and from VoIP subscribers and the

PSTN/PLMN



1 Echo can also be an issue for PSTN integration. Common causes of echo

include impedance mismatches in analog circuitry and acoustic

coupling of the transmit and receive signal at the receiving end.


PSTN

1 Originally a network of fixed-line analog signal|analog telephone

systems, the PSTN is almost entirely Digital data|digital in its core and

includes mobile phone|mobile as well as landline#Fixed phone|fixed

telephones.


PSTN

1 The technical operation of the PSTN adheres to the standards created by the ITU-T. These

standards allow different networks in different countries to interconnection|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.


PSTN - History

1 However, a bell was added soon for signaling, and then a switch hook, and telephones took advantage of the exchange principle already

employed in telegraph networks. Each telephone was wired to a local telephone exchange, and the exchanges were wired

together with trunking|trunks. Networks were connected in a hierarchical manner until they

spanned cities, countries, continents and oceans. This was the beginning of the PSTN,

though the term was not used for many decades.


PSTN - History

1 The growth of the PSTN meant that traffic engineering (telecommunications)|traffic

engineering techniques needed to be deployed to deliver quality of service (QoS)

guarantees for the users. The work of Agner Krarup Erlang|A. K. Erlang established the

mathematical foundations of methods required to determine the capacity requirements and configuration of

equipment and the number of personnel required to deliver a specific level of service.


PSTN - History

1 In the 1970s the telecommunications industry began implementing packet switched network data services using

the X.25 protocol transported over much of the end-to-end equipment as was already in use in the PSTN.


PSTN - History

1 Several large private telephone networks are not linked to the PSTN, usually for military purposes. There

are also private networks run by large companies which are linked to

the PSTN only through limited Gateway (telecommunications)|

gateways, like a large private branch exchange (PBX).


PSTN - PSTN operators

1 The task of building the networks and selling services to customers fell to the telephone company|network operators. The first company to be

incorporated to provide PSTN services was the Bell Telephone Company in the United States.


PSTN - Regulation

1 In most countries, the central government has a regulatory agency|regulator dedicated to monitoring the

provision of PSTN services in that country. Their tasks may be for example to

ensure that end customers are not over-charged for services where monopolies may exist. They may also regulate the

prices charged between the operators to interconnection|carry each other's traffic.


PSTN - Network topology

1 The PSTN network architecture had to evolve over the years to support increasing numbers of subscribers,

calls, connections to other countries, direct dialing and so on. The model developed by the United States and

Canada was adopted by other nations, with adaptations for local

markets.


PSTN - Digital channels

1 The call is switched using a ISUP|call set up protocol (usually ISUP)

between the telephone exchanges under an overall routing in the PSTN|

routing strategy.


PSTN - Digital channels

1 The call is carried over the PSTN using a 64 kbit/s channel, originally designed by Bell Labs. The name

given to this channel is Digital Signal 0 (DS0). The DS0 circuit is the basic granularity of circuit switching in a telephone exchange. A DS0 is also known as a timeslot because DS0s

are aggregated in time-division multiplexing (TDM) equipment to

form higher capacity communication links.


PSTN - Impact on IP standards

1 Voice quality over PSTN networks was used as the benchmark for the

development of the Telecommunications Industry

Association's TIA-TSB-116 standard on voice-quality recommendations

for IP telephony, to determine acceptable levels of audio delay and

echo.


Internet telephony - PSTN integration

1 Most VoIP implementations support E.164 to allow calls to be routed to and from VoIP subscribers and the

PSTN/PLMN


Internet telephony - PSTN integration

1 Echo can also be an issue for PSTN integration.Packetcable Implementation P557– Jeff Riddel– ISBN 1-58705-181-8

[http://books.google.com/books?id=8CNBbrxytcACpg=PA557lpg=PA557dq=PSTN+gateway+VOIP+impedance+mismatch Google Books Preview] Common causes of

echo include Impedance matching|impedance mismatches in analog circuitry and acoustic coupling of the transmit and

receive signal at the receiving end.


IP Multimedia Subsystem - PSTN Gateways

1 A PSTN/CS gateway interfaces with PSTN Circuit switching|circuit switched (CS) networks. For

signalling, CS networks use ISDN User Part (ISUP) (or Bearer

Independent Call Control|BICC) over Message Transfer Part (MTP), while IMS uses SIP over IP. For media, CS

networks use Pulse-code modulation (PCM), while IMS uses Real-time

Transport Protocol (RTP).https://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html

IP Multimedia Subsystem - PSTN Gateways

1 * A Media Gateway (MGW) interfaces with the media plane of the CS

network, by converting between Real-time Transport Protocol|RTP and PCM. It can also transcode when the codecs don't match (e.g., IMS might use Adaptive Multi-Rate|AMR, PSTN

might use G.711).


Routing in the PSTN

1 'Routing in the PSTN' is the process used to route Telephone|telephone calls across the public

switched telephone network. This process is the same whether the call is made between two phones in the

same locality, or across two different continents.


Routing in the PSTN - Relationship between exchanges and operators

1 The PSTN is not a fully mesh networking|meshed network with every operator

connected to every other - that would be both impractical and inefficient. Therefore calls may be routed through intermediate operator networks before they reach their Destination routing|final destination. One of the major problems in PSTN routing is determining how to route this call in the most cost effective and timely manner.


Teletraffic engineering - In PSTN architectures

1 The traffic measurement (telecommunications)|measurement of traffic

in a public switched telephone network (PSTN) allows network operators to

determine and maintain the quality of service (QoS) and in particular the grade of

service (GoS) that they promise their subscribers. The Network Performance|performance of a network depends on whether all origin-destination pairs are

receiving a satisfactory service.



1 Exchanges in the PSTN make use of trunking concepts to help minimize

the cost of the equipment to the operator. Modern switches generally have full availability and do not make

use of grading concepts.



1 A very important component in PSTNs is the Signalling System No. 7|SS7 network used to route signalling

traffic. As a supporting network, it carries all the signalling messages necessary to set up, break down or

provide extra services. The signalling enables the PSTN control the manner in which traffic is teletraffic routing|routed from one location to another..


Internet phone - PSTN integration

1 Echo can also be an issue for PSTN integration. Common causes of echo

include Impedance matching|impedance mismatches in analog

circuitry and acoustic coupling of the transmit and receive signal at the

receiving end.


BeoCom - BeoLine PSTN and BeoLine ISDN

1 The Mark 1 BeoLine can support up to six BeoCom handsets of different types (provided that the BeoLine software has been brought

sufficiently up-to-date).[http://www.beoworld.org/prod_detai

ls.asp?pid=1234] Beoworld site description of Mark 1 PSTN base The Mark 2 BeoLine can

support eight BeoCom handsets, but only those of recent

manufacture.[http://www.beoworld.org/prod_details.asp?pid=1235] Beoworld site description of

Mark 2 PSTN basehttps://store.theartofservice.com/itil-2011-foundation-complete-certification-kit-fourth-edition-study-guide-ebook-and-online-course.html

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PSTN .

Documents

pstn services

standard pstn networks

ip pstn integrationecho

largest pstn subscriber

different networks

voip subscribers

interconnected networks

protocol networks