CallWave has released a new freeware mobile software/service called Cell Phone 2.0. It allows you to screen voicemail messages as they are being left on your mobile phone, transfer those calls to your home/office phone, receive voicemail messages by email, and take cell phone calls over your computer (even when your mobile phone is turned off)

Then you can check your voicemails with the following methods-

Check messages from your cell phone,
Listen to the voicemail attachments emailed to you
Listen to the voicemail messages stored in the client
Call a toll-free number