Help needed with zapata.conf and zaptel.conf

I have a TE110 card and and TDM04B card in my Asterisk server. We use to have 24 channels on our T1 line but changed it recently to only 12 channels. I have been having some random problems since then and want to make sure I configured it correctly.

I had it configured in zaptel.conf as:
e&m=1-24
fxoks=25-28

and in zapata.conf as:
signalling=em_w
channel => 1-24

signalling=fxo_ks
channel => 25-28

How do I configure it for the 12 channels only? Do I change it to 1-12 and leave the fxo’s on channel 25-28? Was just wondering what about the channels 13-24, are they basically dead channels?

Thanks.
Gerhard.