AASTRA 6731 automatically downloads new firmware

I purchased several used AASTRA 6731 phones, the say “please log in” on the display, when I factory default them they go back to their previous state, when I put them in web recovery mode and reload the firmware, if they find a way out to the internet they download new firmware and go back to “please log in”, how is this possible?? I have tried everything!

You have almost certainly got some hardware with a “provider locked” firmware, the only possible solution, and that not guaranteed, is to redirect the instrument’s network request for tftp provisioning (that would be any traffic on UDP/69 from the phone to anywhere) back to your own local tftp server on your own nework. Unless you know how to do that, it would probably be cheaper on your time and money to throw them away, they cost as little as 20 bucks apiece on ebay for “clean” ones and your time is worth how much an hour?

I could use policy based routing on my adtran to accomplish it, I agree with the time thing… I can also use them on a network with no DHCP server and change the default gateway to 0.0.0.0 I guess. Thanks for your help. there are no markings on the phone so it baffles me