Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
1998-05-12
2001-05-08
Maung, Nay (Department: 2744)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C455S426100, C455S550100
Reexamination Certificate
active
06230024
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to wireless communications and more particularly to transmitting digital faxes over a wireless communication link.
2. Description of Related Art
Under current wireless communication systems, a person wishing to transmit a facsimile often originates a call to the recipient just prior to transmitting the fax. Thereafter, the person must release (terminate) the voice call and must redial the same number as the voice call through the digital fax device (eg., personal computer with a digital fax board or a digital fax machine) to set up a line to transmit the facsimile from a system capable of transmitting information in a digital form. The method in the current art is inefficient in terms of resources and user time. Additionally, if a wireless communication medium is being used, then the user may pay for line charges which are not actually used as a result of these inefficiencies. More particularly, because of billing procedures which typically round up all charges to next minute, any user which needs to talk to a recipient prior to sending a fax will always pay for an additional amount of rounding in billing procedures because of the fact that two calls had to be placed to deliver one fax. Additionally, the mere time involved from such inefficiency causes users to be less efficient with our time and therefore increase the cost of labor unnecessarily. While any one such event may not cost a significant amount in terms of inefficiencies, the accumulative totals for such inefficiencies are noteworthy. Accordingly, there is a need for a system and method which allows a user to transmit a digital fax over a line which was initially established for a voice call.
SUMMARY OF THE INVENTION
The foregoing limitations of the current art is solved by creating a mobile station and a base station which allow an ongoing voice call to be converted to a digital fax call. Accordingly, a user can convert a call to a digital fax call without having to hang up, release a voice line (trunk), and redial to establish a digital fax line. Wireless telephone resources and labor efficiencies are improved, therefore. To achieve this desireable result, the base station is adapted to include logic which allows it to listen and be responsive to the receipt of a facsimile indicator signal, such as a calling fax tone signal, from a public switched telephone network (PSTN). As is known to a skilled in the ART, this calling fax tone signal indicates that a device in a PSTN seeks to originate a fax call. Accordingly, even though a voice call is in place, the base station takes steps to generate and transmit signals to set up a digital fax call between it and a digital fax device.
In effect, the described sequences cause the voice call to be converted to a digital fax call. The invention also includes a mobile station whose logic circuitry is adapted to cause it to initiate a digital fax call even though a voice call is in place upon the occurrence of one of two events. The first event is the receipt of a PSTN generated fax tone. One known signal of this type is a “Calling tone” (CNG). If, by way of example, a calling tone was passed through to the mobile station by the base station and if the base station has not yet initiated any signals to convert a voice call to a digital fax call, the mobile station initiates the necessary signals. Stated simply, the mobile station converts a call from the PSTN to a digital fax call if the base station has not yet initiated the transition to a digital fax call even though it passed the Calling tone through to the mobile station. In general, the Ring Indicator or RING result code signal is sent by the mobile station to ask a digital fax device to start the fax answering procedures.
The mobile station also initiates the signals to convert a voice call to a digital fax call when it receives a specified command from a personal computer or other digital fax device that is connected to the mobile station by a line such as a serial digital line. The specified command indicates that the digital fax device is attempting to transmit a digital fax. For example, the mobile station may receive an ATD command (without a dial string) or an AT+CSO=n, where n is the service option for digital fax command. Either of these commands may be used by the digital fax device to request that the mobile station initiate service negotiation to fax.
As may be seen, the invention not only includes the hardware modifications within the base stations and the mobile stations whose logic circuitry is adapted to accommodate this capability, but also includes specific methods for accomplishing the same. In general, new signal sequences are created to achieve a desired result. Additionally, the relative arrangement for sequences of known signals is modified to achieve the desired result. In general, the methods include setting up a digital fax call over a given communication path even though a voice call is already established on that communication path. The call may be set up a result of either a base station or a mobile station receiving a CNG tone(an analog tone) specifying that a device coupled to the PSTN desires to transmit a facsimile. Additionally, the inventive methods include the transmission of an ATD Dial command without a dial string or an AT+CSO=n command. Accordingly, the use of a Dial AT command without a dial string or AT+CSO=n command also is used to indicate to a receiving device that an ongoing voice call is to be converted to a digital fax call. As may be seen, therefore, the introduction of some of these new signals as well as the rearrangment of the sequence of known signals allows a wireless communication network to convert a voice call to a digital fax call without relinquishing a given communication link. As such, network efficiencies are increased and operational cost as well as labor cost are decreased.
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Manning Serge
Mizell Jerry Louis
Wang Chung-Ching
Crane John D.
Harrison James A.
Maung Nay
Nortel Networks Limited
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