Method for Direct Attachment of a Data or Stored Voice Device to a Public Switched Telephone Line
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
A method is described which allows the attachment to the public telephone network of a computer data device or a stored voice device to meet the Federal Communications Commission (FCC) attachment requirements with a minimal amount of hardware circuitry. A direct attachment interface to a telephone line for a data or stored device must perform the following functions: 1) Provide isolation and surge protection that satisfies FCC requirements 2) Couple voice band energy to and from the telephone network. 3) Control the DC current on the network to provide an off-hook indication. 4) Convert a two-wire circuit to a four-wire circuit. 5) Detect the ringing signals from the telephone network. 6) Eliminate excessive levels of transmitted signal. 7) Provide a two-second delay before transmitting data or non- live voice.