An Internet Call Waiting--Voice over Internet Protocol (ICW-VOIP) service
that uses a service control point and service node of a Public Switched
Telephone Network (PSTN), acting as a gatekeeper and bridge respectively,
to enable ICW subscribers to answer telephone calls during an internet
session without having to disconnect internet access. The primary network
components of the ICW-VOIP service comprise a proxy firewall, a service
node, and a gateway. When a PSTN call is placed to a subscriber whose
line is being used for internet access, the service control point
accesses the subscriber's internet address from a database and transmits
a message over the internet to the subscriber giving the subscriber the
option to accept the call as a VOIP call. Once accepted, the subscriber
places an H.323 call through the gateway to the service node. The service
control point also forwards the PSTN call to the service node. Using
bridging information, the service node matches the subscriber H.323 call
and PSTN call and bridges them together to provide a VOIP connection.