How I Can Increase The Modem Rings in NT

I Have A Modem , Us Robotics Careir 56 K , External
And It’s Pluged To NT Server 4 .
And RAS Has Been Started .
The Problem Is ,, When I Dial In To the Modem ,, It’s Ansering The Call Imediatly .
So I Want the Modem To Anser The Call After 4 or 5 Rings ,,
How I can Do That ?
I serach All The Data Base About Us Robotics And Nothing Work .
I Hope U Can Answring Me ..

Regards