Ping clients with one ring

I wanted to buy a 8 line licence of auto-dialer, but I miss one function. The thing I want to do is to ping clients that they call back me. Is is possible to let it just ring one time or a few seconds instead of waiting that the telephonee takes the call?

Yes. You can set the option from Gateway main menu > Setup > Options > Advanced tab. These options are:

1. Disconnect after x rings, and
2. If not answered, disconnect after x seconds after dialing

Can I give every sende number I like or do I have to speak about this with my VoIP provider? Thank´s in advance for your help.

If you are talking about Caller ID display, then yes, you need to talk to your VOIP provider.