How Can I Convert dtmf card signal coming from teliphone/Mobile to keyboard output?

Some modems have the facility to detect and translate DTF tones but they dont usually go into the keyboard buffer directly.

There are some softwware systems using TAPI which can detect DTMF but will need something on the line that can listen to the tones.

Try Asterisk. its basically a mini phone system on a computer.
http://www.asterisk.org/

The question is, what kind of solution are you looking for? Algorithm, library, circuit?

In DTMF, each key is determined by two tones transmitted simultaneously, one is related to row and one is related to column of pressed key (for details see for example http://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling). So for you have to detect eight tones in total. Usually in software decoders the Goertzel algorithm is used: http://en.wikipedia.org/wiki/Goertzel_algorithm.

If you are looking for a solution by external circuit, you may have a look to http://www.farnell.com/datasheets/79191.pdf (HT9170, formerly known as MT8870). It does a complete decoding, with output of 4bit binary number identifying one of 16 possible keys pressed plus one pin going high when the tone is present.

thanks sir for your valuable comment, i want to know how i will integrate this device in computer this device will be connected with ps/2 port or which port so that when device convert dtmf signal into binary numeric value that should be directly sent to windows game application. i am wating for your response.
once again thanks for giving your valuable time.

I have understood, that you have analog audio signal (carrying DTMF tones) and you want to translate tones to PS/2 keyboard input or some other keyboard connection port (e.g. USB).

Typical way to achieve this is to use some small microcontroller (MCU), such as PIC, AVR, ARM, ... you could use the HT9170 decoder, connect it to GPIO pins of the MCU. For PC connection I would recommend you USB.
Many of today's MCUs contains peripherial of USB slave and their manufacturers provide drivers and examples that help you to implement your application. Want you would use is so called HID class device. HID (Human Interaction Device) is USB class for sending events like key presses or mouse movements.

You can connect several HT9170 DTMF decoders to one MCU to handle multiple analog channels.

Particular device you can use is (for example) this one with ARM core: http://ics.nxp.com/support/documents/microcontrollers/?scope=LPC1311 here is application note regarding USB HID: http://ics.nxp.com/support/documents/microcontrollers/zip/an10904.zip
I can also recommend you this evaluation board http://uk.farnell.com/nxp/om11048/kit-dev-lpcxpresso-lpc1343/dp/1777673 (LPC1343 is similar to LPC1311 mentioned before, except it has larger memories).

how will i connect HT9170 DTMF decoders to MCU? is it possible through cable or what? and if it does how can we connect mcu to computer?
kindly help i am very new in programming of harware integration

thanks

please also send some link where can i buy mcu? and also suggest which kind of mcu available in market for this kind of work? any particular model name of mcu?

looking for your help sir, please help me.

thanks thank u very much

> how will i connect HT9170 DTMF decoders to MCU?

MCUs have pins for connecting devices like this, you can use almost any of them, for details see MCU's datasheet.

> is it possible through cable or what?

Common way is to solder them on PCB or connect using breadboard.
http://en.wikipedia.org/wiki/Printed_circuit_board
http://en.wikipedia.org/wiki/Breadboard

> and if it does how can we connect mcu to computer?

I have tried to describe it in my last post. If you use microcontroller with integrated USB slave peripherial, you have to just connect the MCU to computer with USB cable and write appropriate firmware for MCU using provided drivers - please see links in my previous post.

> kindly help i am very new in programming of harware integration

I see. Did you intended to do this kind of work? Is my solution too complicated for you?

> please also send some link where can i buy mcu?

Please see the link to Farnell in my previous post. There you can find evaluation kit I recommend to you for first experiments. Also you can buy there standalone MCU and other components needed.

> and also suggest which kind of mcu available in market for this kind of work? any particular model name of mcu?

Please see links in my previous post, I have already done this.

thank you so much for your help sir, now i will try to implement the system