local VOIP managers

• Fonality – http://www.fonality.com/
• 3CX – http://www.3cx.com/
• http://www.yeastar.com/

Cloud PBX

• RingCentral
• Vonage
• http://jive.com/
• https://www.digium.com Switchvox
• http://www.broadvoice.com/