Philips Se655 Quattro - phones wont ring!

Hello,
we have just bought the Philips SE655 Quattro, have followed all the instructions on setting up the phones, but unless we have saved a number in the phone memory and assigned it a ringtone then if somebody else calls, it doesnt ring! Philips dont no wot the problem is! We returned the set and the new one has hust arrived and is doing the exact same thing! Please help!!!!