Plain old telephone service

POTS is an acronym for "plain old telephone service " (English for " plain old telephone service", transferred about " the good old telephone service" ). This retronym has naturalized in the jargon as a designation for the analog telephone service. This is not to be confused with an analog subscriber line, hanging on a continuous digital telephone network.

The term " POTS " was originally a joke name for PSTN (Public Switched Telephone Network, for English: Public telephony switching networks ) that emerged from the " Post Office Telephone Service " ( telecommunication services of the post). However, this term also fits the newer digitized and enriched with advanced service features telephone network, which was forming itself to distinguish a formulation that only describes the service features ("Services" ), which could also be provided by the old analog telephone service.

Compounds in POTS

The compounds in POTS ( Plain Old Telephone Service) can be distinguished in their characteristic service features from other forms of telecommunications service.

  • POTS line is completely based (switched ) with duplex cables for voice traffic with 0.3 to 3.4 kHz (as opposed to packet-based Internet).
  • The participant selection is done using a video relay service (information ) or by an autodialer, such as keypads or number switch.
  • The connection established between two end points is exclusive and independent services. Except the language, other data can be exchanged with a modem, such as a fax.

The service features of POTS, in the first analog sub-networks obtained by switching a direct electrical connection between the subscribers, wherein the switching points for an electric bridge is set between the two telephone cables, which are connected to a switching element. The direct line was built undivided per connection, the damping of the material, however, was only matched for suitability in the frequency range of the language, so that a multiple use tight bounds were set. Other applications such as district clerk regularly had their own distribution networks with their own tuning and suitable switching elements, which were not used for POTS connections.

Integration in the ISDN

The often run parallel sub-networks for POTS connections and distinct, services brought the drive to merge them into one integrated telecommunications service with sharable line networks. The possibilities of digitalisation of switching nodes and the digitized signal transmission reached in the 1970s, the telephone networks and eventually led in 1980 to the creation of an international standard for an integrated services digital network ISDN shortly.

ISDN integrates POTS connection using transparent channels. A sampling rate of 8 kHz, digitized voice band, the scanning steps are individually transmitted byte ( 8 bits ). The switched digital connection can also be used for other data (8 kHz × 8 bits = 64 kbit / s). The choice of method of connection setup and release remain the same for the participant.

It is possible to connect analog sub-networks by digitizing in an ISDN switch. Thus, an analog network are digitized gradually. By integrating the POTS service features in ISDN ( Wish formula " BORSCHTs " ) can still analog connection lines are provided ( for conventional analogue terminals ) that are identical to the " good old telephone service" behave by a subscriber circuit. In Germany, the public telephone networks have since completion of digitization in the fall of 1997, no analog subnets more.

Extension of POTS

A number of advanced call processing features of the digital core network were subsequently made available for analog subscriber ports. About special number sequences of three conferences can ( 3PTY ) are set up and a call to busy subscriber (CCBS ) are initiated. An additional signaling ( FSK signal ) is also a Caller identification ( CLIP) was possible, but this required a ( new ) electronic devices for analogue phone lines. Other service features were available but limited quality - so missing on analogue terminals Dedicated controls for controlling the voice mailbox, the speed dial list or received SMS messages, but a controller is via speech synthesis of the relevant elements of the intelligent network (IN) fundamentally possible. Through these extensions, a current analog subscriber port on the digital core network is no longer identical to the terminals on old consistently analog telephone networks that were the basis of the POTS - term education in its scope of services.

  • Telephone network
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