has abstract
| - AT&T Merlin is a corporate telephone system by American Telephone and Telegraph (AT&T) that was introduced in late 1983, when it was branded American Bell Merlin. After the breakup of AT&T in 1984, it was rebranded and later also supplied by Lucent and Avaya. The system was designed at the beginning of the 1980s prior to the Bell System Divestiture as a modern electronic replacement for the dated electromechanical 1A2 Key System. Earlier Bell attempts at an electronic key system, such as Horizon and Dimension, were not as successful as were the much larger systems; in fact, Dimension was a PBX. The Merlin was the first small electronic system, replacing the Com Key 416. The Merlin system was originally sold in two-line, six-telephone (206); four-line, 10-telephone (410); and eight-line, 20-telephone (820) configurations. Later, there was a further 10-line, 30-telephone configuration, and with the addition of an expansion key service unit (KSU) the system could accommodate up to 30 lines and 70 telephones available (1030 and 3070 respectively). Later, the Merlin Plus created a system initially configured for four lines and 10 phone extensions with built in Feature Modules previously purchased as a separate module on the original 206, 410, 820, and 1030 control units. Merlin Plus was expandable to up to eight lines and up to 20 phone extensions. For larger installations, AT&T System 25 PBX was an advanced digital switching system that integrates voice and data communications. It was designed to meet the business communications needs of customers in the 30 to 150 station range. And it not only provided the features of a state-of-the-art private branch exchange (PBX), but also allowed data to be switched point-to-point without first being converted to analog format. This capability was used to set up connections between data terminals, word processors, personal computers, and host computers. The system provided 256 ports to support the following:
* 115 simultaneous two-party conversations
* Traffic Handling Capacity of 4140 CCS (Trunking Limited)
* Busy Hour Call Capacity of 2500 calls (DTMF Register Limited)
* Up to 104 trunk ports including Central Office (CO), DID, Tie, Foreign Exchange (FX), Wide Area Telecommunications Service (WATS), and 800 Service
* An Auxiliary Trunk interface for paging and dictation systems
* Up to 240 ports that support a combination of the following:
* Up to 200 ports for voice terminals and auxiliary feature port equipment.
* Up to 104 data ports providing RS-232 connections to data terminals, personal or multiport computer. Merlin systems were administratively programmed and customized using special dial codes and button presses through the phone connected to extension port 10 with the phone's T/P switch moved to the P position. Unlike the smaller Merlin systems, System 25 was programmed using a System Administration Terminal (SAT). The SAT was a dedicated, password-protected computer terminal continuously connected to the RS232 serial port to the PBX. The default password was systemx5. (en)
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