ISDN switeches & Gateways

Dear sirs,
I have an idea and I want to implement it,
I have heard somethings about ISDN gateways and ISDN switches
bitween analog telephone lines and isdn lines.
I want use my analog lines as ISDN lines by using an
interface (ie. ISDN switch).
Is it possible or is there any solution for this ?
would you please help me, or guide me to some useful
resources ?

Best Regard