Hello, I bought 3 of the Samgoma S505 used from ebay. They work However when I try to change to my sip freepbx they revert back to the old settings that was from the old owner. They no longer are in business. But how do I stop it from reverting back.
You need to make Factory reset of each phone how to @Ducktour suggested… Also login at your Sangoma Portal → My Products → Sangoma Phones → Claim it for your FreePBX ZendID
from this way you can start to use for Zero Touch Provisioning (1st step )