I use AnswerAmerica and they're alright. Sometimes I get a good person answering the phone and the client thinks it was a girl at my front desk sometimes the person can barely understand them. I do always get my messages though and they get sent by e-mail and text instantly. Much better than an answering machine and it's around $1/call with no contract.
Good luck with them. I've been using them for a while and overall I give them a 7/10, but sometimes the people they have answering the phone are just not professional. If you try them out for a little while let me know how it works for you.