This document provides the view of Telcordia on generic requirements for the CLASS feature Outside Calling Areas Alerting (OCAA).
This feature allows a customer to receive distinctive alerting for incoming calls originating from outside the customer's "local
calling area." The local calling area is defined on a per-switch basis as a list of Numbering Plan Area (NPA) and NPA-XXX codes, and
does not necessarily have to correspond to any particular geographic or billing boundaries. Distinctive alerting to idle lines is
provided via a special ringing pattern, which can be provided in addition to any Calling Identity Delivery capability.
Distinctive alerting to busy lines is provided via interaction with any Call Waiting features to which the customer is also
subscribed by providing a special call waiting tone. In addition, OCAA can be configured to provide a Call Waiting interaction for
"outside" calls only, and options are given to
specify the OCAA treatment on inter-SPCS (Stored Program Control switching System) calls for which the calling area is