A local switch includes circuitry for determining whether a called party is a subscriber of a call type delivery service when a call is being placed to the called party. The local switch also includes circuitry to generate a message to prompt the calling party to identify whether the call is urgent,...http://www.google.es/patents/US6031899?utm_source=gb-gplus-sharePatente US6031899 - Method and apparatus for identifying type of call
