Best voip provider

Ok, so right now I currently use vonage

I have two lines, one voice, one fax.

I want to switch services to a company that I can setup an asterick’s server.

I was checking out Teliax, VoicePulse, Broadvoice. I want kinda the same setup, two lines. Which company do you guys recommend? VoicePulse and BroadVoice are kinda confusing about the amount of lines. I want the option to add more lines as I need. What company do you guys recommend?