How to assign an extension to a channel on a Rhino FXS bank?

Using a Rhino FXS channel bank, how do I go about assigning which
extension goes to which channel on the bank? And how easy is it to
switch them around? x.

Thank you

Assuming the T1 is your only DAHDI card it would simply be addressed 1-24

I am planning on having 4 channel banks here. Plus one T1 card for voice communication.