Are you using LLDP on your Network Switches? Are the phones being assigned to a VLAN? Is it possible UDP helper is not assigned to the Routing interface on the VLAN so that the phones are not able to obtain IP addresses? What version of firmware is on the phones? Are you able to use Wireshark on the Network to see if there are any DHCP requests reaching the DHCP Server?
Thanks for your reply, I will look into the LLDP issue. Still not sure why though it only happens on some of the 715's , most of them work like I would expect, as far as obtaining DHCP addresses. They are being assigned to a VLAN. The firmware that they arrived with is 184.108.40.206, however even after an upgrade to .35 the defective ones still don't work unless static.
Now, what about the NTP issue? Every D715 phone experiences this, after a reboot it clears the NTP settings. Doesn't matter what IP I put in there. After a reboot it is reset to 0.0.0.0 ?
thanks for your help!
Is it possible your DHCP Server is configured to provide option 42 and passing 0.0.0.0? Are you provisioning the ntp_server setting?