Service Evaluation System
Encyclopedia
The Service Evaluation System (SES) was an Operations Support System
developed by Bell Laboratories and used by telephone companies beginning in the late 1960s. Many local, long distance, and operator circuit-switching systems provided special dedicated circuits to the SES to monitor the quality of customer connections during the call setup process. Calls were selected at random by switching systems and one-way voice connections were established to the SES monitoring center.
During this era, most voice connections used analog trunk circuits that were designed to conform with the Via Net Loss
plan established by Bell Laboratories. The purpose of the VNL plan and five-level long distance switching hierarchy was to minimize the number of trunk circuits in a call and maximize the voice quality of the connections. Excessive loss in a voice connection meant that subscribers may have difficulty hearing each other. This was particularly important in the 1960s when dial up data connections were developed with the use of analog modems. The SES evaluated multi-frequency
outpulsing signaling as well as voice impairments including sound amplitude, noise, echo, and a variety of other parameters. Deployment of Common Channel Signaling
systems such as Common Channel Interoffice Signaling and later Signaling System #7 obviated the need to monitor multi-frequency
signaling as it became obsolete.
The Service Evaluation System was described in Notes on the Network
published by AT&T
in 1970, 1975, 1980 and later versions published by Bell Communications Research (now Telcordia Technologies
) in 1983, 1986, 1990, 1994, and 2000.
Operations support system
Operations support systems are computer systems used by telecommunications service providers. The term OSS most frequently describes "network systems" dealing with the telecom network itself, supporting processes such as maintaining network inventory, provisioning services, configuring network...
developed by Bell Laboratories and used by telephone companies beginning in the late 1960s. Many local, long distance, and operator circuit-switching systems provided special dedicated circuits to the SES to monitor the quality of customer connections during the call setup process. Calls were selected at random by switching systems and one-way voice connections were established to the SES monitoring center.
During this era, most voice connections used analog trunk circuits that were designed to conform with the Via Net Loss
Via Net Loss
Via Net Loss is a network architecture of telephone systems using circuit switching technologies deployed in the 1950s with Direct Distance Dialing and used until the late 1980s. The purpose of the VNL plan and a five-level long distance switching hierarchy was to minimize the number of trunk...
plan established by Bell Laboratories. The purpose of the VNL plan and five-level long distance switching hierarchy was to minimize the number of trunk circuits in a call and maximize the voice quality of the connections. Excessive loss in a voice connection meant that subscribers may have difficulty hearing each other. This was particularly important in the 1960s when dial up data connections were developed with the use of analog modems. The SES evaluated multi-frequency
Multi-frequency
In telephony, multi-frequency signaling is an outdated, in-band signaling technique. Numbers were represented in a two-out-of-five code for transmission from a multi-frequency sender, to be received by a multi-frequency receiver in a distant telephone exchange...
outpulsing signaling as well as voice impairments including sound amplitude, noise, echo, and a variety of other parameters. Deployment of Common Channel Signaling
Common Channel Signaling
In telephony, Common Channel Signaling , in the US also Common Channel Interoffice Signaling , is the transmission of signaling information on a separate channel from the data, and, more specifically, where that signaling channel controls multiple data channels.For example, in the public switched...
systems such as Common Channel Interoffice Signaling and later Signaling System #7 obviated the need to monitor multi-frequency
Multi-frequency
In telephony, multi-frequency signaling is an outdated, in-band signaling technique. Numbers were represented in a two-out-of-five code for transmission from a multi-frequency sender, to be received by a multi-frequency receiver in a distant telephone exchange...
signaling as it became obsolete.
The Service Evaluation System was described in Notes on the Network
Notes on the Network
Notes on the Network is a publication created by the American Telephone & Telegraph company beginning in 1970. AT&T published later versions in 1975 and 1980. This document was maintained and published by Bell Communications Research in 1983, 1986, 1990, 1994, and 2000. For the current version,...
published by AT&T
American Telephone & Telegraph
AT&T Corp., originally American Telephone and Telegraph Company, is an American telecommunications company that provides voice, video, data, and Internet telecommunications and professional services to businesses, consumers, and government agencies. AT&T is the oldest telecommunications company...
in 1970, 1975, 1980 and later versions published by Bell Communications Research (now Telcordia Technologies
Telcordia Technologies
Telcordia Technologies, formerly Bell Communications Research, Inc. or Bellcore, is a telecommunications research and development company based in the United States created as part of the 1982 Modification of Final Judgment that broke up American Telephone & Telegraph...
) in 1983, 1986, 1990, 1994, and 2000.