A digital direct access arrangement (DAA) circuitry may be used to terminate
the
telephone connections at the user's end to provide a communication path for signals
to and from the phone lines. Briefly described, a means for providing a proper
hookswitch transition for a variety of international phone standards is provided.
The invention may also be utilized with means for transmitting and receiving a
signal across a capacitive isolation barrier. More particularly, a DAA circuitry
may be utilized which satisfies many or all hookswitch transition standards without
the use of additional discrete devices. The hookswitch transition standards may
be satisfied by ramping down the current flowing through the hookswitch prior to
transitioning the hookswitch state. In this manner the hookswitch current change
as a function of time (di/dt) may be decreased. Thus, the current through the hookswitch
may be actively controlled prior to switching the hookswitch from an off-hook condition
to an on-hook condition. By controlling the current drawn from the phone lines
through the hookswitch, the maximum voltage seen at the phone company exchange
may be decreased.