IPhone application (if possible)

Hi this is just to first check if this is possible.

Wanted to know if you could build an app that would allow you to only allow certain calls to come through after say 6pm allowing you to use one number for work and business.

I know the iPhone has a "do not disturb" feature, but this is more for a business contact you have listed would go straight to voicemail after a set time you specify.

Please do not give copy and paste bids without having an idea if this is possible.

Cheers.