Connect CCME to triple play solution

Hi all, 
At home I have a triple play internet offer that includes Internet, TV and free phone (local and international !!!)
So my idea is to connect my router fxo port to my Internet box, and  then allow all IP phones in the house to call through this line.
Even I've studied my CCNA Voice teadiously and passed, it's still blurry how to connect CCME to the PSTN. 

You would be very welcome if you had any real life video to achive this.

Cheers

Alex