T-1—24 Voice or Data Paths Over One Telephone Circuit

The T-1 multiplexing scheme was developed by AT&T in the 1960s as a way to save money on cabling between telephone company switches by enabling one circuit to carry 24 voice or data conversations. (A circuit is a path for electrical transmissions between two points.) The technology was not made available directly to end-user locations until 1983.

In the mid-to-late 1980s, large organizations such as universities, financial institutions and Fortune 100 companies used T-1 circuits to tie locations to host computers for applications such as order entry, payroll and inventory. The T-1 often replaced having to physically carry large computer tapes between locations. Once installed, companies found ...

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