<xhtml:p>The invocation of handleNotReachable requests the application to
inform the gateway how to handle the call between two addresses, the
callingParty and the calledParty, where the calledParty is not
reachable when the call is received. Optionally, the callers name is
provided. The application returns the action, which directs the
gateway to perform one of the following actions:</xhtml:p>
<xhtml:p>Optionally, in the action parameter, the application can also
indicate the charging information.</xhtml:p>