Dialogic Corporation

Allan Ashmore

Maciej Wasiel

John George Shaheen

Michael J Rus

Forward error correction is implemented in a facsimile transmission using adaptive redundancy. The depth of redundancy can change based on a number of factors, including lost packet counts, transport type, facsimile modulation type, call history or facsimile engine state changes. Separate redundancy depths can be implemented for image and for control phases of the facsimile call. Redundancy depth can be increased or decreased during a facsimile call, and may be maintained at an increased level once encountered transmission impediments are overcome. Variable redundancy can be provided for specific portions of the call, such as temporarily increased redundancy during control phases. Adaptive redundancy may be implemented at one or more endpoints or nodes in a packet-switched communication network through which the facsimile call passes. The adaptive redundancy contributes to improving successful facsimile call completion in communication networks that may be prone to error losses.

Adaptive facsimile redundancy

Timers involved in facsimile transmissions under the T.30 specification are permitted to adapt to a given situation to improve the chances for successful facsimile transmission over high latency communication networks. The specified T1 through T5 timers for facsimile transmission may be modified in value based on call control related parameters or facsimile transport related parameters. The timers may be set to have a particular range, with a nominal base value and a maximum value, which may exceed the T.30 timer specification. The adaptive timers can be modified based on a number of different criteria related to facsimile transmissions to avoid overlapping command-response situations and stalemates that may result from communications in relatively highly latency networks. The timers may also be adapted to minimize or optimize call length while achieving successful facsimile transmissions.

Adaptive fax timers which adjust current time value based on predicted response time

Communication network components can be synchronized for facsimile transmissions in the communication network. The synchronization may compensate for variations in transmission rates among the different network components or different paths taken by portions of the facsimile transmission. The synchronization may involve modulating an adaptive jitter buffer or an effective packet rate to compensate for clock skew that may occur between network components. The compensation to obtain synchronization can be achieved to avoid causing interruptions or distortions in the facsimile transmission data. By applying the compensation at specific points or intervals in a facsimile transmission, synchronization can be achieved to obtain an overall quality improvement in facsimile transmissions in a packet switched network.

Compensation for facsimile transmission in a packet switched network

A wireless communication device can send and receive realtime facsimile transmissions over a data channel available to the device. The device can implement a real time facsimile protocol over the data channel, which can generally be a packet switched network connection, such as an IP connection. An image capture device can be employed to obtain an image of a document that can be facsimile transmitted from the wireless device over the data channel. The document image may be converted to a format generally usable with facsimile transmissions. The wireless device can be configured to transmit immediately following image capture, or after a desired number of images are captured. A contact list that may be included with the wireless device may be used to select a destination address for facsimile transmission. A printing device can be the destination address to permit wireless or mobile printing.

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North Grafton, MA, United States of America

Allan Ashmore