Abstract: This invention allows enterprises to achieve specific objectives in the management and enforcement of policies related to the use of telecommunications services. It was conceived for use in connection with traditional telephone networks that carry voice, facsimile or voice-band-data (VBD) traffic, though it is not necessarily limited to such networks. It involves measurement of the properties of traffic on a communications channel, and the use of such knowledge in combination with various ancillary properties of telecommunications service usage to guide the conditional performance of prescribed actions based on user-defined policies. The measured traffic properties include classification of the type of traffic, where the set of possible classes include zero or more classes selected from a group of general categories comprising Voice, Facsimile, Voice-Band-Data, DTMF, Audible Network Signaling, Facsimile Handshaking, Voice-Band-Data Handshaking, Silence and Unknown.

Abstract: A method of clock recovery from a fast packet switched asynchronous network wherein a time stamp is transmitted over a network that has variable delay, involves maintaining an input counter at a sending device. The counter has a value dependent on an input clock. The value of the input counter is periodically transmitted over the network to a receiving device. A local counter at a receiving device has a value dependent on a local clock. The received value sample x.sub.i is compared with the local sample y.sub.i to derive the difference e.sub.i. The local clock frequency f.sub.j is adjusted such that the average of Emin.sub.j, where Emin.sub.j is the minimum of a block of error samples e.sub.i, remains close to a predetermined value, preferably zero. The clock recovery method is particularly suitable for MPEG2 video transmitted over ATM.

Abstract: An apparatus and method is disclosed for performing policing functions for specialized telephone services, and for mitigating fraudulent usage of such services in ubiquitous telephone networks that carry voice, facsimile or voice-band-data traffic. Signal processing is used to determine the properties of traffic present on a channel at a given point in time, and actions are conditionally imposed based on such traffic properties. A first embodiment of the invention can be applied to prevent fraudulent use of telephone services through suppression of an answer supervision response. A second embodiment of the invention can also be applied for regulation of access to specialized telephone services which depend on the manner of customers' use of such services.

Abstract: A method and apparatus for detecting and classifying signals that are the additive combination of a few constant-amplitude sinusoidal components, herein called N-tones. The attributes of this method and apparatus include provision of superior classification performance with an algorithm of low computational complexity. The method includes filtering to remove extraneous signal components, separation of the incoming signal into one or more output streams and segmenting these output streams into blocks of successive data samples. The magnitude of the data within each block is estimated along with the frequencies of the dominant spectral components. The frequency estimates are then used as part of the configuration process of a set of notch filters for removal of the identified dominant spectral components. The newly-configured notch filters are then applied to the same data blocks and the magnitudes of their outputs are estimated.