The bt 4500 additional handset the high quality gap compatible dect handset for the bt 4500 big button cordless phone this is an additional handset and charging cradle for use with an existing system item cannot be used without a base station main unit available herebrand new handset with full warranty in plain packinghandset will need to be manually registered to the main base upon arrival please refer to manual for the main phone or contact our customer services for assi