This is a problem on more than just LG.
Samsung and Motorola models have the same issue.
I did everything they told me to do and nothing worked.
Brought it to one of their stores that flash phones, still no resolution.
Their solution is to pay to get another phone.
It is not the phones.
It is a carrier setting they need to check for incoming ring time before VM.
To any Metro tech that reads this thread, if and when you figure out a resolution, please let us know.