AltiServ H-PBX is the first affordable Hosted IP-PBX for multi-tenant organizations supporting up to 99 separate organizations and 400 users per AltiServ system server. AltiServ H-PBX is an overlay software application applied to 4.6 and later versions of AltiWare OE. AltiServ H-PBX is modular allowing larger MultiTenant organizations or installations to add multiple AltiServ H-PBXs servers as needed to accommodate growth.