Hello there

Read the self help center.

There are two requirements 1. You must have three reviews (I'm sure you knew that). You have that covered. 2. You have to have a board posting presence. #2 isn't stated anywhere I'm aware of. I know it because providers are often asking about the Provider Only board and later report they were denied because of little or no board presence. I'm guessing thats what TER told you. Only they know how much is enough.

If there is, admin doesn't let us know what that number is anyway. They just say you need an established posting history. (plus 3 reviews, which you obviously have)  All you can do is post on the boards, then ask for admittance again. Join in discussions on your regional board or some of the general discussion boards. I would say to try to post a few times a week at least, then ask for admittance again after a month. The worst that will happen is they will say no, you need more posts.

They probably gave you a time frame to request admittance to the PO board again, keep posting on the boards to establish a presence and ask again. It just takes a little patience, chances are you'll get in if you continue to play by their rules and jump through their hoops. Good luck!

and that one is 7 months old. While you have met the 3 review criteria, it is possible that you will need some current reviews along with board posts before they are comfortable enough to allow your entry.

it says "TER may consider additional information based on your history before granting access as this is an unmoderated board."  It does not specify exactly what information but about the only other thing is posting history.