Dial through an app - but hide the "call" screen

Hi,

I plan to make an app that gives a missed call to my company's number, and at a convenient time the company gives a call back.
Is there a way that this missed call can be given in background (i.e. it hides the "Phone" to come up), and the client continues to see my app all the time, thus giving a seamless interface. If it cannot be done, then when my app gives a missed call, the screen will switch from my app page to the "call screen", which is something I want to avoid.
Your help can save me a lot of time.
I understand that it can be done by sms, but I prefer a missed call as it is zero cost to client.
Thanks