Same as first post for me. Goes to voicemail then says mailbox is full.

Receiving calls from this number on a somewhat daily basis but they never leave a message.  I called it back today and receive the message that the voice mailbox is full.

It's a Google phone number.  You can access the account by pressing the "STAR" button and entering the passcode of 1111 and then you can change any info you want but there are no voicemails stored in the account.

Called July 19th @ 8:37. Didn't answer and no message