Is it possible to force a 5410 that has rel6 on it to downgrade to rel5. I have an ip500 on 4.1.15 and the phones say system incompatible. I already added the allow upgrade for 5410's, rebooted they system, I made sure the directories were pointed to the 4.1.15 software. I even tried to trick they by renaming the 5410-R5 to 5410-R6. I can't get them to take the older files. Any ideas? The phones work, I connected them to a newer system and they came up fine.