PhoneView software on a Mac or TouchCopy for PCs will work. A Google search should bring up the developer sites for either. Last I saw a few months ago, they were both in the $25-30 USD range. I've used PhoneView for years; less familiar with TouchCopy, but a friend bought it a while back for the exact same reason, and we were able to preserve her voicemails on the PC very easily. Good luck!