Only the current version so far — new entries appear as the app ships updates.
Smart PBX is a business app by NTT DOCOMO BUSINESS, INC. with 100,000+ downloads (about 118K estimated). +271 installs in the last 7 days. Released Jun 19, 2014. Install growth, rank history, SDKs and ad networks.
From the store listing: “[Overview]
Smart PBX is an IP phone service that you can use on your smartphone. It is a mobile device service that is provided as a major additional function of mobile communication services such as "OCN Mobile ONE for Business" and dedicated line services such as "Arcstar Universal One" provided by NTT Docomo…”