Unfortunately, carriers will not allow the forwarding or transferring of voicemails from one service to another. This will work if you are able to get a hold of the audio files, which can be moved to your YouMail inbox.
YouMail's Drop Box features can be used to forward voicemail audio files to YouMail. However, please note that the audio files are needed in order to make this work.
The YouMail team is currently looking into finding a way of making this transfer or forwarding possible for our members.
Click here to learn more about using YouMail Drop Box.