Abstract: A system suitable for encoding typographic characters into two digit base ten values and to decode such values to typographic characters are disclosed. The system maps typographic characters, such as letters in the English language and puctuation symbols into two decimal digit numeric codes. The mapped numeric codes allow all upper and lower case English letters to be identified by a unique two digit code, that may be encoded using conventional DTMF tones. The system similarly decodes two digit numeric codes, so encoded. The system optionally include a DTMF generator and decoder. Methods used by the system are also disclosed.

Abstract: A system and method are presented for sending a message from one telephone to another by transmission of a short code. A set of message units stored within the receiving telephone is assigned to a set of codes which may be transmitted. The receiving telephone is a code-compatible telephone configured to detect an incoming code and forward the corresponding message unit to an output device associated with the code-compatible telephone. A message unit may comprise an entire message, or a portion of a message, such that multiple message units are combined to form a message. The message units may be alphanumeric or non-alphanumeric. An alphanumeric message unit contains multiple alphanumeric characters, while a non-alphanumeric message unit may contain graphical or auditory information. An alphanumeric or graphic message unit is forwarded to a display screen on the code-compatible telephone if the corresponding code is received. An auditory message unit is instead forwarded to the telephone's loudspeaker.

Abstract: A method and system in a network telephony system for transporting audio signals with lower delay when DTMF is not present. The method of transporting audio signals determines whether DTMF signals are included in the audio signal, or are likely to be transported according to the called or calling parties. A delay is imposed in the audio when DTMF signals are sensed or determined to be present as indicated by the calling party, the destination telephone number, the called party, and various other indicators. A timer may be used to trigger a reduction and elimination in the audio delay after an initial period in the call for calls in which DTMF signaling is used for an initial period of the call. The timer may also trigger the reduction and elimination in the audio delay when no DTMF signals have been received after a period of time. The system uses a DTMF detector to sense DTMF signals in the audio signal and to signal the delay generator to impose a delay in the audio stream.

Abstract: The emergency call such as Enhanced 911 call or the like is also originated through an exchange such as PBX (Private Branch Exchange). In this case, the identification information such as the extension number of the extension telephone terminal connected to the PBX should be transmitted to a network corresponding to the emergency call. For the extension telephone terminal, it is necessary to unhook or to capture an arbitrary line by the line key, before inputting the dial data “911”. Independent of the capture of arbitrary line, the PBX searches a vacant line connected to the network corresponding to the emergency call, captures the vacant line, transmits the identification information such as the extension number, and switches over and connects the extension telephone terminal from the line captured by the terminal to the vacant line.

Abstract: A method of generation and detection of acoustic signals carrying alpha-numeric data for reducing the effects of noise and thereby improving signal transmission without the need to boost the power of the signal. In accordance with one aspect of the invention, a special DTMF acoustic signal consisting of a combination of two frequencies will be generated for the representation of a particular alpha-numeric character that will be similar to the standard DTMF tone. The difference between the amplitudes of both frequencies varies during the time of generation of the DTMF tone in such a way that both signals will arrive at a final destination detector, i.e., an interactive voice response board, at least for a portion of the generation time, at a relatively similar amplitude, thereby substantially increasing the probabilities of being recognized as a DTMF signal.

Abstract: The present invention utilizes common hardware and software routines already present in most digital telephone devices, e.g., a DTMF detector; to download data over a telephone line to a digital telephone device. Each symbol of a numeric system, e.g., a hexadecimal system, used to represent the data is associated with a DTMF tone pair. The DTMF tone pair is downloaded from a data source such as a manufacturer of the digital telephone device, to the digital telephone device using a telephone line. Other tones may be used to provide control signals between the data source and the digital telephone device. Thus, using common and inexpensive routines in a typical digital telephone device, the expense of a modem or other conventional data communication device is not necessary to receive data.

Abstract: A videophone apparatus with an on-screen telephone keypad user-interface. The videophone communicates video and audio data over a plain old telephone service (POTS) line and includes a video source and a communication channel interface circuit coupled to a programmable processor. The programmable processor is configured and arranged to execute a user interface program for user controlled operation of the videophone apparatus, display a first menu on the display, the first menu referencing a first plurality of options for operating the videophone apparatus and having associated therewith respective indicators of telephone keypad buttons, receive from the telephone keypad a first selection signal indicative of a pressed button, and initiate an operation to control the videophone apparatus in response to the first selection signal.

Abstract: A modem that operates reliably at a symbol rate that corresponds to twice its bandwidth even when it is coupled to a receiving A/D converter that operates under control of a clock is realized by synchronizing the modem's operation to the A/D's clock. The superior operation of this modem advantageously extends to A/D clock frequencies beyond the frequency of twice the modem's bandwidth. To minimize quantization noise, the modem's output is conditioned to minimize intersymbol interference by adjusting the modem's output to the A/D converter's sampling times and slicing levels. When the A/D's clock is higher than twice the bandwidth of the modem's output signal, some intersymbol interference cannot be avoided. In accordance with this invention, the position and value of this interference is computed at the receiver and subtracted from the received signal.