I have been looking for a solution for this for some time.. and I think I have found some thing that might fit... Panasonic do a range of cordless phones, that will do things like 'call bar' & and 'night mode'.. this site has a 'quick features list' and usually a link to the manual!
http://www.home-phones.co.uk/home-ph...era-ansaphone/
or panasonic support here _ note they have a rather strange 'classification system' so you may have to look around a bit!
http://www2.panasonic.com/consumer-e...l.KX-TG9341T.H
The key thing is 'night mode' - you can set a time period for when the phone will NOT ring! - you can also set numbers from the phonebook to bypass this, for important calls..