Contact your carrier and have them suspend your voice mail feature.
Then instruct people to send you a text if your phone doesn't answer.
I have a personal 1 800 number that I forward my calls to which allows me to receive faxes as well.
My voice mails can be emailed anywhere I choose in MP3 format. I can block not only phone numbers but also area codes, prefixes or partial numbers. If someone trys to obfuscate their number by using call blocker I see their number anyway. I find owning a toll free number offers many advantages that Google Voice doesn't. The downside is that it cost 7 cents a minute for incoming calls but my bill rarely goes above $6 a month.
I'm really just looking to prevent calls from telemarketers and unknown callers from going to voicemail, I guess I will have to resort to either let it go to voicemail or use the answer/hang up technique
I am quite annoyed at being unable to Block calls from Unknown Callers