I've used Kall8 and RingCentral. While I'd generally recommend RingCentral (especially if you use a lot of minutes), it depends on your requirements. Kall8's

I've used Kall8 and RingCentral. While I'd generally recommend RingCentral (especially if you use a lot of minutes), it depends on your requirements. Kall8's advantages over RingCentral: - Recorded calls - Can get the name of the caller through caller ID (RingCentral only offers the phone number) RingCentral's advantages: - Much, much cheaper. RingCentral Office gives you unlimited minutes (well, realistically it's about $20 for 5000 minutes because they have "fair usage limits", so you have to buy more lines if you use more) - Allows for simultaneous dialing. This is critical if you want your 800 number to be answered immediately. I've never used Kall8 or RingCentral for digital lines, by the way, so I'm not sure how well they work in that case.