I have discovered a small pin hole on the bottom fight underside of Cisco 79xx model phones.Can anyone tell me it's use?Is it possibly for a hardware factory reset?

I have many (1720) model 7960 Cisco phone registered OK on my CUCM running V7.1.2.I have trouble installing a 7960 on the system. It goes throught configuration cycles and reports error "file not found P00303010102.The CUCM in Device Defaults, Load I...