Android Question How to make a phone call from my application only without the dail dialog to appear

Hello;

I would like to add one feature to my application which to let my customer choose a service from the application and place the order by calling my work 800 number and pass the service code to the ivr system which will record the service code and the phone number that the customer called from.

I am able to do that but the phone dialing screen comes up. I would like to make the call without the dialing screen of the phone to come up.

your help is very much appreciated