Sending DTMF Tones

8 Apr 2005 11:11 AM

Florian Göttsch

Hi,

I have the following problem:

I must send a DTMF tone "A" for at least 3 seconds. But i can only find
solutions for sending tones with a normal length ( about 200ms ).

In Details:

I have a client that is calling a server. Both are using DTMF-Tones to
communicate. The Server must identify himself to the client with a special
tone "A". This tone must be within the first 3 seconds of the call. And this
tone has to be at least 3 seconds.

If im using DirectX, it takes a long time to initialize. So the Tone is not
within the first 3 seconds.

Using .wav-files for generating the tone does not work, because of the
quality. The client does not recognize the tone then.

Does anyone have an idea ?

Thx,

Florian Göttsch

p.s. Sorry for my english.

8 Apr 2005 1:06 PM

Chris Dunaway

You can use a program such as Goldwave to create wave files with pure
DTMF tones with high enough quality.

Ideally, however, you'll want to get a telephony board of some sort and
use a toolset such as NCT's DialogicVoice control. Check out their
site: www.nctsoft.com.

You can programatically generate tones using that control.