Packet Switched | A form of data transmission in which data is broken into small packets that
are transmitted independently and reassembled at the destination. This is in
contrast with circuit-switching, traditionally used for voice telephony, in
which the transmission occurs over a dedicated circuit.
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PBX | A PBX (Private Branch Exchange) is a private telephone switch that provides
switching for an office or
campus. A PBX allows telephone extensions to connect to each other as well as the outside world.
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Point of Presence (POP) | The physical place within a LATA where a long distance carrier or a cellular
provider interfaces with the network of the local
exhange carrier.
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Port |
- The physical, electrical, or software interface through which a device gains access
to a network or computer.
- Network access point for data entry or exit.
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POTS | See Plain Old Telephone Service.
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Primary Interexchange Carrier (PIC) | The long distance company to which traffic is automatically routed when an
end user dials 1+ a telephone number.
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Primary Rate ISDN (PRI) | PRI is a 4-wire 1.544 megabits per second (DS1) local switching system port
that uses the B8ZS line code and the ESF framing format. PRI is available in
a twenty-three B channel plus one D channel (23B + D) configuration or a twenty-four
B channel (24B) configuration.
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Private Branch Exchange (PBX) | A private telephone switching system commonly located on the end user premises
with an attendant console. The PBX is connected to a common group of lines from
one or more central offices to provide service
to a number of individual phones
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Proxy | A SIP proxy server can be stateless or stateful. A stateful proxy acts as a virtual UAS (User Agent Server) or UAC (User Agent Client).
The SIP proxy takes over call control from the terminals and serves as a central repository for address translation (name to IP address).
The SIP proxy server provides similar functionality to a gatekeeper in an H.323 environment or a softswitch in an MGCP/MEGACO environment. |
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PSTN | PSTN stands for public switched telephone network. It represents the vast network of circuit switched equipment used by the Telephone company.
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Public Safety Answering Point (PSAP) | An answering location for 9-1-1 calls originating in a given area. A PSAP may
be designated Primary or Secondary, which refers to the order in which calls
are directed for answering. Primary PSAPs respond first; Secondary PSAPs receive
calls on a transfer basis only, and generally serve as a centralized answering
location for a particular type of emergency call. PSAPs are staffed by employees
of Emergency Response Agencies (ERAs) such as police, fire or emergency medical
agencies or by employees of a common bureau serving a group of such entities.
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Public Service Commission (PSC) | State regulatory agencies for utilities (including telecommunications); various
state agencies have names such as Public Service Commission, Public Utility
Commission, Board of Public Utilities, Public Service Board, Dept. of Telecommunications
and Energy.
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Public Switched Telephone Network (PSTN) |
1.The worldwide voice telephone network.
2. Any common carrier network that provides circuit switching among public users.
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