Sending a handshake tone through voice modem

[lukeyboy]

Hi All,

I's just like to know whether it is possible to get a modem to generate tones for me, namely tones at 1400Hz and 2300Hz. I wan't to use a modem to interface to a piece of equipment I have, but to do this properly, I need to send those two tones.

The equipment will dial my modem, and will look like a voice call. The research I have done tells me that I can get my modem to act like an answering machine, so this should not be a problem. I want to send my triggering tones, and then read data from the modem, which is sent from my equipment in DTMF. Nobody seems to be able to help me so far, so I'd love to hear from anyone who can help!

Cheers

 

[pansophic]

What you are asking for is relatively simple, but the AT commands may change based on the modem type. The example that I will give you works if your modem supports mode 8, not 8.0.

AT#cls=8 ; Put your modem in voice mode
OK
ATDT nxx-nxx-xxxx ; Dial your number
VCON
AT#VTD=FF,FF,FF ; enable detection of all tones
OK
AT#VTS=[1400,10] ; Send 1400 Hz for 1 second
OK
AT#VTs=[2300,8] ; Send 2300 Hz for 800 ms
OK
AT#VTS=[1400,2300,22] ; Send 1400/2300 Hz for 2.2 sec
OK
AT#VTS=3,4,5 ; Send DTMF 3, then 4, then 5
OK

Your receive data will will be DTMF, which you have already set your modem to detect.
<DLE>0 ; DTMF 0
<DLE>1 ; DTMF 1
...
<DLE>* ; DTMF *
<DLE># ; DTMF #
<DLE>A ; DTMF A (4th column digit)
<DLE>B ; DTMF B (4th column digit)
<DLE>C ; DTMF C (4th column digit)
<DLE>D ; DTMF D (4th column digit)
<DLE>a ; Answer tone (2100 Hz) from fax/modem
<DLE>d ; Dial tone received

If you are not familiar with ASCII codes, <DLE> is the data link escape character: ^P, or 0x10, or 16. You'll be keying off of it.

To find out which mode that your modem works in, try AT#CLS=? and it should show you all of the modes. Expect something like 0,1,2.0,8. Where 0 is data mode, 1 is type 1 fax, 2.0 is type 2.0 fax and 8 is voice. If you get ERROR, then try AT+FCLASS=?. The response should be basically the same, except you will see a mode 8.0 for voice.

In that case, you need to cross reference these commands against the 8.0 standard. It shouldn't be too difficult, but the commands will be more like AT+VTS.

pansophic