Virtual PBX Hosting
Voice Mail
Fax -to -email
Softphones Support (Smartphone / Tablet / PC / MAC)
IVR ( Options. Ex: For english.... press 1) 
Virtual Conferences Rooms
Record Calls
Least cost routing
Ext Roaming (apps required)
Interconnetion between PBXs
Caller ID
Call Forward
Transfer extensions
Hold (with music)
And more....