I just came across Private Phone. This is a site where you can get a free phone number and voicemail. If you already have a telephone and internet access then you can just sign up, get your additional phone number and check your voicemail over the phone or online. I found out about this on the wahm forum so I think I am going to give it a try.
Here is a link to their faq
If you have experience with this or know of any other sites, please leave a comment.