In an organization using Adtran Netvanta 7100 PBX, the system firmware on the Netvanta 7100 was updated to R11.4.2.E. After the Netvanta 7100 firmware update, changes to Voice User Accounts could not be made unless the phone model was updated. In this case, 2 more line keys needed to be added on a Polycom IP 650 phone. The phone model was changed to ADTRAN/Polycom IP 650 from the drop down menu under IP Phone Configs. The changes were then applied successfully. However, upon rebooting the phone, changes made to the phone’s configuration were not taking place. Reset to Default – local configuration had no effect. Reset to Default – Device Settings placed the phone in a reboot loop. Ultimately, reviewing the MAC ADDRESS.cfg file for that voice account and comparing it to that of a working unit, revealed that it was missing an entry. In the MAC ADDRESS.cfg file, under CONFIG_FILES=”polycomboot.cfg, customer-sip.cfg, customer-sip-MAC ADDRESS.cfg, customer-sip-spip650.cfg, adtran-sip_40x.cfg, xxxx-MAC ADDRESS.cfg”/> it was missing SIP.cfg. Once sip.cfg was added between quotes the phone booted normally and changes applied to the phone’s configuration were in effect.