Below are links to documentation pertaining to Cisco phones.
***Please be aware our support of these devices is limited. We do not support them in the conventional sense like we do Polycoms. We are able to build configuration files for the phones to pull. We manage the config files. We do not maintain firmware and we do not offer replacement devices unless the client opts for a Polycom.***
The following is basic information relating to Cisco phones. This page also contains links to additional reference materials such as Cisco 7900 Series Feature Matrix, Supported Star Codes Matrix, and MOP_Provisioning Cisco 7900 Series Phones
http://support.evolveip.net/index.php/2015/04/cisco-ip-handsets/
The following is a generic guide that can aid in walking a client through facotry defaulting a Cisco/Linksys phone.
X Cisco Phone Factory Default - How To
The following is a reference to pertinent information related to configuring Cisco/Linksys phones.
The following is in reference to deleting the security profile on some model of Cisco phones.
X Deleting the security profile on Cisco 7945 or 7965 IP Phone