I have CCM 4.1(2) and using 3750 switches for DHCP. I often have this problem that when my phones (7912G) boot up, there directory services option is missing although the TFTP server IP (CCM in my case) is mentioned in dhcp configuraton under dhcp option 150. What I do is to delete the dhcp pool from the switch, clear the dhcp bindings and arp cache, re-insert the dhcp pool and restart the phone. This always bring back the dc directory option. Any solution to this? Thank you.