My clients Call manager express has been unregistering phones and I have been unable to solve this problem. I am using the image c2800nm-advipservicesk9-mz.124-15.T1.bin. So far 6 phones have unregistered. At on point the show ephone output showed that a phone is 'deceased'. when I try the phone in with our office call manager it works fine. The phones get stuck at 'Configuring CM List'. There are 84 phones connected to the Cisco2851 router. It has been working for 8 months very well until recently. What is the way forward?