Browse Prior Art Database

Dual Tone Multi-Frequency Simulation in a Handheld Computer/Telephone Device

IP.com Disclosure Number: IPCOM000117547D
Original Publication Date: 1996-Mar-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Meyer, PG: AUTHOR

Abstract

Disclosed is a method for initiating a telephone call from a handheld integrated device including a computer system and a telephone by issuing a command to the internal modem of the system to go "off the hook," and by subsequently generating the Dual Tone Multi-Frequency (DTMF) tones with an algorithm within the system. These tones, which identify the location being called to the public telephone network, are generated by an audio device driver in the system, or by facilities of the operating system to play a sound file containing pulse code modulated waveform data. These tones are passed from the computer sound Input/Output (I/O) through the voice I/O lines within the modem.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 68% of the total text.

Dual Tone Multi-Frequency Simulation in a Handheld Computer/Telephone
Device

      Disclosed is a method for initiating a telephone call from a
handheld integrated device including a computer system and a
telephone by issuing a command to the internal modem of the system to
go "off the hook," and by subsequently generating the Dual Tone
Multi-Frequency (DTMF) tones with an algorithm within the system.
These tones, which identify the location being called to the public
telephone network, are generated by an audio device driver in the
system, or by facilities of the operating system to play a sound file
containing pulse code modulated waveform data.  These tones are
passed from the computer sound Input/Output (I/O) through the voice
I/O lines within the modem.

      Without this method, the computer system issues AT commands to
the modem, which generates the DTMF codes to reach the desired
telephone number.  However, a typical modem has a poor capability to
produce a tone code for a dial single digit, as required by many
switching systems after the telephone connection is made, and a poor
capability to produce a tone in response to momentary control.  Thus,
without the presently disclosed method, the computer system is
restricted to a loosely-coupled interface that cannot respond well in
real time to selections of displayed "buttons" by the user with
finger motions on a touch-sensitive screen or with a pointing device,
such as a pen (stylus).  The momentary opera...