Hi amrick1
Thanks for posting in regards to your voicemail service for your mobile, we appreciate you taking the time to raise this via the forums and welcome to the community.
In regards to the call back, there isn't a feature in the voicemail service that allows you to call the customer back directly from the message, the number would be mentioned in the automated part of the message that the call was from. There is some voicemail help here in regards to set up, troubleshooting and how to use 🙂
Thanks
Rob