In there you will find all the answers on licensing (you can connect as many phones as you like of whatever model you like up to the license limit), WAN interconnect limits if using FXO or T1 (there are no limts for SIP Trunk (only bandwidth SLA from SIP runk SP), COnference configuration (you can addjust how many members and how many conferences you want (Adhoc and Meetme; where 32 is the max in any one) and voice mail box sizes (total minutes can be sliced up as you want it (steal from the kitchen phone to pay paul).
Configure Multicast Paging on the Cisco IP Phone 7800 Series or 8800 Series Multiplatform Phone
The Cisco IP Phone 7800 and 8800 Series Multiplatform Phones provide voice communication over an Internet Protocol (IP) network...
Add Call Park on a Cisco 7800 or 8800 Series Multiplatform Phone Key Expansion Module
Call park allows the user of the phone to put an incoming call on hold so that the call can be retrieved on another phone. A call is park...