The Yeastar P-Series Ultimate Plan 100 Extensions UP package P-SE-UP-Pro is a package of the Yeastar P Series PBX Ultimate Plan for 100 extensions.The Ultimate Plan enables advanced features for the P Series PBX System. It includes everything from the Ultimate Plan, including, full-featured offerings for Call Center, Remote Access Service, Instant Messaging, CRM Integration, plus video conference and web video calls.