Google Voice keeps getting blocked

[lorem]

Google Voice is occasionally blocked. When I look at Live sessions I see two blocks:

The first Blocked Domain is stun.l.google.com. Block message is Conferencing category
If I allow all of Conferencing category, stun.l.google.com is still blocked

The second Blocked Domain 74.125.39.xxx (xxx = it changes). App protocol is STUN Protocol. Block message is Network Management category
There is no STUN Protocol in Network Management category. In App Controls -> VOIP -> VoIP STUN was already enabled.

I can individually enable these in Live Sessions -> Blocks. But Google occasionally changes a port or address setting and then I silently lose incoming calls until I discover I can't make a call. Besides allowing everything which would defeat the purpose of Zenarmor, I don't see any way to fix this.