a wireless packet communication system conforming to the ieee 802 . 11 standard includes a plurality of access points most of which have wired connections only for power and an isdn telephone line . the aps communicate at 8 . 5 ghz with a regional point - of - presence that is one end of a vpn through the internet to a national office . the registered users &# 39 ; data and control of the system including the ip assignment and sip proxy and the control of the 802 . 11 communication reside in the national office . by retaining for a short period the sip connection , ip address and key encryption information after a user has disassociated from an ap , the user can quickly reauthenticate and reassociate using the same sip connection , ip address , and encryption key at a different ap . voice data and computer data can both be processed through an ap by the addition on another 802 . 11 frame encoder / decoder .