link telephone system

i have a avaya ip500 system with no voip license acting as our PaBX. we are moving to a new building and taking up two floors. is there a way to link the bottom floor telephone extension to the rack which will have our IP500 server. intial thinking was to have two uplinks.

just wondering will the uplinks be enough to transfer call to the below extension? or do i need some other hardware or software to cater for this.

need help and ideas