Can I recover a deleted voicemail on my iPhone?
Yes it's possible to recover some deleted voicemails. However, it all depends on your carrier, and the age of the voicemail you're trying to reclaim. To find your deleted voicemails, open the Phone app, tap Voicemail, and scroll down to the bottom of the page until you see the words "Deleted Messages". If you do not see the Deleted Messages panel, then there are no messages to recover. To see what deleted voicemails are available, tap the Deleted Messages panel and it will bring up a list. Tap the voicemail you want to save, then tap the "Undelete" button.
You can also clear any saved deleted messages by hitting the "Clear All" button at the bottom.