asterisk users - Apr 2005 - How to avoid CTL file request for Cisco 7970

Hi All!
We buy Cisco 7970 and have a problem. At startup phone requests CTL file 
and hangs with message
"Updating CTL". Nothing more happens after it. I tried to place dummy 
file with the name
CTLSEP<mac addr>.tlv to TFTP root directory. Cisco found it and then 
message changed to
"CTL update failed" and startup process stops.  Some people here told 
that they can succesfuly
register this phone on Asterisk.

What can I do to avoid this problem?