I'm installing a Norstar BCM 400 with all IP phones. 20 IP phones will be at the main site. 6 of the IP phones will be at a remote site 500 ft away. The network between the buildings is connected by a cat5e cable.I am going to upgrade the main site switch to QOS, and will install either a hub or another QOS switch, if necessary, at remote site. Is it necessary to buy a QOS switch for the remote site as well, or will a hub suffice?

Is 500 ft too far away for the 6 remote IP phones to work off the main QOS switch? Do I need a data extender of some kind?