7921 Web interface

You can configure the 7921 phone using the phone keypad, or use a comfortable Web interface...
You can get a USB cable that connects your 7921 to your local PC. Installing the driver on your PC creates a virtual network interface on your PC. Give it any address in the 192.168.1.0/24 network (except 192.168.1.100), and you are ready to open an https session to your 7921, which is listening at https://192.168.1.100. Check here for more details on how to install the USB driver, install with Windows is sometimes... interesting...
http://www.cisco.com/en/US/docs/voice_ip_comm/cuipph/7921g/6_0/english/administration/guide/7921cfgu.html

From the Web interface, you can monitor your phone and configure many items such as WLANs and anything else you would configure using the phone keypad... this is "if" you have write access to your phone via the Web interface... how does that work? This is where it gets easy:

1. If the phone is set to factory default, you can access with Read/Write rights without restriction. Use the credentials admin/Cisco to access the phone configuration pages.

2. If the phone has already registered to a Communications Manager (CUCM), the possibility to Write depends on what configuration was sent from the CUCM to your phone. The CUCM admin may have allowed the Read/Write access... or not! The default is not to allow it, because why would your average user access this interface anyway, hey? They are supposed to USE the phone, not to PLAY with its configuration.
On your phone interface, you can verify if you have Web Read/Write access by going to Settings > Device Configuration > Security Configuration, check if Web Access is set to Full, Readonly or Disabled. You can also try to https to the phone, and see how far you go...

Now, what if you do not have the USB cable... and still want to use the Web interface? Well, that's kind of easy too... create a basic cisco WLAN on your controller (open authentication, no encryption), and reset your phone to factory default (go to Settings > phone settings > type **2 > Click yes to accept the reset to factory default)... the phone reboots, looks for the cisco SSID (that's the default behaviour), associates, and gets an IP address through DHCP. Just HTTPS to that IP address and you are on the phone Web Interface, with full read/Write access.