Can I configure a router to control access from my children's telephones as well as other devices?

Our children use both I-phones and Motorola phones. We get worn down by the fights about "confiscating" the phones, and want to be able to block access to the Internet on a device-by-device basis when we need to. Is there a router or other device/configuration that can control access on such a basis?

Thanks.

Ken J., New Jersey