Force a busy signal

My lines are setup to for call forwarding on busy. On occasion I would like to be able to force my lines to be busy so my call forward will activate. Is there a simple way to enable this with analog trunks?

thanks

Loop them but don’t dial. Your PSTN provider may treat this as a fault condition.

I want to forward my main analog trunk to another number after hours. *72 and *73 doesnt work. I am thinking that as each call comes in we check the day and time. If it is after hours or weekends then the calls get routed to the other number otherwise they get handled as usual.

is this doable and is there maybe a better way to do this?