How to send dtmf signal through mobile keypad?

[Sibtain]

i just wanted to find out that when we pressa button the mobile what is sent to the other side is the keypad a dtmf one sending a voice baseband signal or something else
secondly
do all mobiles and land line phone keypads use the same frequencies for a key
thank you

 

[VSMVDD]

mobile keypad

dtmf is a standard
and many systems use it

a standard is a standard so yes all phones that use dtmf will use the same dtmf waveforms

ctcss is mostly the same thing in america and others

a good thing to play around with is a keyfob dialer

it uses dtmf but outputs to audio
so you can dial a number thru the reciever

all the time ... on interrupt the phone network controller listens for dtmf traffic

they cost about £1

you can wire a pic too one and make a project for telephone number store or something

 

[Sibtain]

keypad dtmf

please tell me if there is a cm5089 chip in mobiles

 

[throwaway18]

how to take dtmf signal from mobile

i just wanted to find out that when we pressa button the mobile what is sent to the other side is the keypad a dtmf one sending a voice baseband signal or something else

In modern digital mobile phone systems such as GSM when you type a number and press the connect
button the phone number is sent with digital signalling not DTMF. When a call is already connected
the number buttons send DTMF which is carried as a digitised and compressed audio stream

>ctcss is mostly the same thing in america and others

CTCSS is not the same thing.
CTCSS is not used in telephone systems.

>please tell me if there is a cm5089 chip in mobiles

Digital mobile phones do not contain an IC just for DTMF.
You might find a DTMF chip in a very old analog cellular phone that was made
twenty years ago.

 

[ezshereef]

ezshereef

Salam,

Take care that you can't send DTMF on mobile lines, that is to say if you played a DTMF at the mic of one side of the call and received it from the other side it will not be interpreted as a DTMF. as throwaway18 said the DTMF signals are sent on the mobile network as digital signals and the mobile that receives the tone regenrates the tone for human interface or may be a machine that will receive that tone. if you are willing to send DTMF tones on the GSM line so you might connect your mcu to the mobile and send AT commands to it.

you can use the command "AT+VTS="
for more information you can look in the following link.


salam
shereef

 

[Sibtain]

send dtmf from mobile

yes you are right but i really dont care in which form the dtmf signal is transfered ,digital or something i am mainly interested in finding out that once if the call is conected and we pressa button than on the speaker of the receiver will it be a dtmf signal or something lose to it ,one thing is for sure that when you pressa button the receiver hears a voice signal of some frequency isnt it .i just intend to connect a 8870 ic at the other end and 8051 controller and activate relays
thank you:?:[/b]

 

[throwaway18]

mobile keypad frequency

Take care that you can't send DTMF on mobile lines, that is to say if you played a DTMF at the mic of one side of the call and received it from the other side it will not be interpreted as a DTMF.

Wrong. Provided the tone is loud enough to be picked up by the microphone at a high enough level and
there is not too much background noise it will work as a DTMF signal.

as throwaway18 said the DTMF signals are sent on the mobile network as digital signals

Read my post again.

yes you are right

ezshereef is wrong.

i am mainly interested in finding out that once if the call is conected and we press a button than on the speaker of the receiver will it be a dtmf signal or something lose to it

It will be a DTMF signal.

 

[artem]

mobile keypad dtmf?

In gsm , when button is rpessed to generate dtmf tone - phone wont do generate the tone - it sends message to gsm switch where it is generated by special dtmf tone generating equipment. If somebody will try to send a tone thorugh phone's microphone the one should be aware that phone voice encoding is synthetis - no one to one frequency spectre transfer . It is due to nature of voice encoding algorithm in mobile systems .
If somebody wants to send pure dtmf thorugh phone - AT command has to be used AT+VTS.
Refer to the actual modem at command reference manual for its at command encoding for more detail.

 

[khaldun904]

Re: ezshereef

Salam,

Take care that you can't send DTMF on mobile lines, that is to say if you played a DTMF at the mic of one side of the call and received it from the other side it will not be interpreted as a DTMF. as throwaway18 said the DTMF signals are sent on the mobile network as digital signals and the mobile that receives the tone regenrates the tone for human interface or may be a machine that will receive that tone. if you are willing to send DTMF tones on the GSM line so you might connect your mcu to the mobile and send AT commands to it.

you can use the command "AT+VTS="
for more information you can look in the following link.


salam
shereef

how i can send 10 tone per second using cellphone the min time iget is 10 tone /5s which is to long , do you know how to do that or a mobile send fast dtmf ??
please help its for my project

---------- Post added at 14:44 ---------- Previous post was at 14:42 ----------

In gsm , when button is rpessed to generate dtmf tone - phone wont do generate the tone - it sends message to gsm switch where it is generated by special dtmf tone generating equipment. If somebody will try to send a tone thorugh phone's microphone the one should be aware that phone voice encoding is synthetis - no one to one frequency spectre transfer . It is due to nature of voice encoding algorithm in mobile systems .
If somebody wants to send pure dtmf thorugh phone - AT command has to be used AT+VTS.
Refer to the actual modem at command reference manual for its at command encoding for more detail.

how i can generate 10 tone per second using at command the max i get is 10 tone per 5 sec which is too long time