Verizon Voicemails reports "Mailbox Full" when reached by outside callers, Box is not actually full

Verizon continues to have issues with IPhone 6, 7 & 8 and their internal voicemail handling. I am seeking a workaround or self help to resolve a repeated "mailbox full" error warning to people calling me when my mailbox is not actually full. I found a temporary resolution by logging into Verizon's voicemail system via *86, and then resaving the two brief messages in my mailbox. There is also still a discrepancy between the Iphone visual voicemail and the Verizon cloud mailbox, there are more messages on the iphone directly than the Verizon Cloud. I am curious to see if the Apple community has any fix for this issue.

My current device and software:

Iphone 7

iOS - 13.4.1