lots of funky configs out there…
If the phone is able to get its IP address over dhcp, its config via tftp, and you have a valid ntp IP address in your config file and you have connectivity to that server and the phone isn’t updating the time at boot you probably have a bug in your config file and may need to start from basics and built up slowly…
reboot sequence – hit the settings key then dial **#**
don’t use the factory reset key sequence unless you have a dhcpserver and tftp server setup and the software to put on the tftpserver … otherwise it will just spin trying to install new default software.
my big hurdle was figuring out that the proxy section of <sipLines><line button=”1″><featureID>9</featureID> wasn’t <proxy>USECALLMANAGER</proxy>
I tried to be special and add the ip address again of my sip server – the behavior of the phone in this mode is to get the SEP<MAC>.cfg.xml file, get the dialplan.xml and do nothing.
Here’s a good reference I found after I was up and running: https://blog.kmp.or.at/cisco-ip-phone-7942-w-asterisk/