Reset IP Phones

You could try a factory reset, hold the # while booting up the phone.

Then press 123456789*0# which will format the flash but will keep the Network config intact.

Or press 3491672850*# this will format flash with wiping out every thing .

When you use 349 key sequences, the phone will have no LCD display at all for more than 20 minutes, pls be patient and wait until it finishes.

Make sure you are on a DHCP enabled network, have the right TFTP server set in Option 150 and most importantly that you have a valid default loads and matching application files on that TFTP server.