Accessing voicemails from a disconnected line on a family plan (that is still active)

About a year ago, I left an AT&T Family Plan and now have Google Fi, but kept the same number. Is it possible to access old voicemails that would have been received/saved while on AT&T? That family plan is still active, just without my old line, so I'm hoping they're still stored somewhere. They are really sentimental and it would be great if there's any way to retrieve them through an AT&T server or if the account holder still has access somehow?

Any advice would be greatly appreciated!