A direct access arrangement (DAA) device is provided that is configured to interface a
security alarm modem with a phone network. The DAA device comprises a receive
optical isolator (OI) module having a receive input side and a receive output side. The receive input side includes a receive input line configured to receive a remote
signal from the phone network. The receive output side includes a receive output line configured to convey the remote
signal to a
security alarm modem. First and second transmit OI modules are provided that each have a transmit input side and a transmit output side. The transmit input sides have transmit input lines joined in parallel with one another and configured to receive transmit signals from the
security alarm modem. The transmit output sides have transmit output lines joined in parallel with one another and configured to convey the transmit signals to the phone network. An
impedance matching module is joined to the transmit output sides of the first and second transmit OI modules and configured to provide
impedance matching with the phone network. Optionally, the transmit output lines from the first and second transmit OI modules may be joined in parallel with the receive input line. The first and second transmit OI modules may include first and second LEDs, respectively, that draw substantially equal
diode currents. The receive and first and second transmit OI modules may each have an associated
diode current, where the receive module is interconnected with the first and second transmit OI modules such that the
diode current collectively utilized by the first and second transmit OI modules changes by an amount that is substantially equal in amplitude, but opposite in polarity, to the diode current utilized by the receive OI module.