using dtmf to transfer data through pstn

[khurram]

hi,
i want to use dtmf to transfer data on telephone line but i donot known what data rate i can acheive

 

[pico]

It's V.18 and V.19 of ITU-T rec.
You can download from
hxxp://wxw.vsi.ru/library/ITU-T/22.html

 

[zorro]

4 bits per digit, and 10 digits per second: 40 bps.
Maybe you can get more than 10 digits per second (see generator and detectors specifications for signal times and interdigit times) but not much more.
Very low bit rate, but it is easy and sure, using standard and cheap components.
Regards

Z

 

[hm_fa_da]

i have used it in some project , duplex data transaction , i send every 60ms , one digit .
but there is a problem ,
sometimes MT8870 (decoder) , doesn't decode data , i solved it with using MT8870 better mark , and now it is less than before .
i used tp5088 as tone generator.

 

[padspcb]

Holly!!!
Back to the sixties?
Dial 1 if fire
Dial 2 if intruder
Dial...
Or wait for operator?????
Today at the cost of $1 per 2Mbytes i think gprs is the go.
And no wiring needed altogether....
How much costs the telephone minute anyway?
...