Put some/all fxo ports out of service for a period of time

Under certain circumstances I would like to put certain/all the FXO ports on the system out of service for a period of time, and then at some point later I would like put the ports back on service again, how do I do it ? Perhaps putting the FXO ports concerned permanently offhook ( until they get onhook again at some point later ) will be the way to do it ? My question is, how do I do it using asterisk configuration ?

Regards.