Superb call quality, a large easy-to-read display screen and user-friendly button layouts/designs make the Cisco phone models of old and late some of the best hardware available for IP-based phone systems.However, for all their outstanding advantages, configuring these phones to work with a non-Cisco managed Vo IP network can be a bit of a chore.This process will delete everything on the phone – certificates, call history, etc – so be warned.(examples here)If the above methods did not work then you’ll likely have to try something more drastic.According to Cisco, when initiating a factory reset procedure certain information from the IP phone is erased while other information is reset to the factory default value, as shown in the list below: Information Erased: It is highly advisable to follow the firmware upgrade procedure in a non-working environment to ensure other phones are not affected (in case of an accidental reboot), and to avoid the freshly factory reset ip phones obtaining the working environment’s settings.Cisco IP phone SCCP firmware files version 9.2., 7965 & 7975 IP phones (latest version at the time of writing this article) are available at our Cisco IP Phone & ATA Firmware Download section. When performing the factory reset procedure we are about to describe it is important to keep in mind that the IP phone will lose all configuration files and phone application.To deploy Cisco Unified Communications Manager Express, network services need to be established and properly configured on all routers and switches for Cisco IP phones to function.
We also provide necessary information on how to setup a DHCP server on a CME router or Cisco Catalyst switch, to support Cisco IP Phones and provide them with DHCP Option 150 so they know where to find and register with the Call Manager or Call Manager Express server.
One of the most valuable and available resources in setting up systems has been peer communities.
Both local and online resources will assist in working the kinks out of your system. A large number of Asterisk / Cisco configuration issues are identified and often fixed here.
Does your Cisco handset not boot, or have some other unexplained issue?
You can do a factory reset and see if that helps (this is usually the last step in troubleshooting before the trash can).