Free incoming wifi (VOIP) calls

What Android apps are available that will give you free wifi incoming calls (VOIP) to either your existing phone number or a separate phone number in a US area code you can specify?

Requirements

• Google Voice is not a desirable option.


• Cost should either be free or less than $15 per year.


• Video is not needed; only audio is required.


• Audio quality must be at least as good as cell network.


• Must be reliable.