The Intelligent Multiservice Access System (IMAS) enables support for the
next generation of virtual connections. Regardless of whether the
communications lines coupled to the inputs and outputs of the IMAS are
based on SVC, PVC, or a combination of PVC and SVC, the IMAS can support
SVCs for a more flexible, timely, efficient, and manageable connection.
In the more typical configuration, the loop side of the IMAS is PVC-based
because the modems do not support SVC signaling, and the
telecommunications backbone side is capable of supporting SVC signaling
even though existing DSLAMs do not employ SVC signaling logic. With SVC
support, the IMAS assists the ATM network in hand crafting an SVC-based
connection almost immediately between end users when the originating end
user wants to make a call to a destination end user, and tear down that
virtual connection almost immediately when that call has completed. The
SVC signaling is performed by a proxy signaling agent that resides in the
IMAS to give the appearance to the ATM network in the telecommunications
backbone that the loop side supports SVC signaling even though the line
is PVC-based.