Follow the steps below.

Unplug the power cable from the phone, and then plug in the cable again.

The phone begins its power up cycle.

Immediately press and hold # while the Headset, Mute, and Speaker buttons flash in sequence.

Release # after the Speaker button is no longer lit.

The Headset, Mute, and Speaker buttons flash in sequence in order to indicate that the phone waits for you to enter the key sequence for the reset.

Press 123456789*0# within 60 seconds after the Headset, Mute, and Speaker buttons begin to flash.

If you repeat a key within the sequence, for example, if you press 1223456789*0#, the sequence is still accepted and the phone resets.

If you do not complete this key sequence or do not press any keys, after 60 seconds, the Headset, Mute, and Speaker buttons no longer flash, and the phone continues with its normal startup process. The phone does not reset.

If you enter an invalid key sequence, the buttons no longer flash, and the phone continues with its normal startup process. The phone does not reset.

If you enter this key sequence correctly, the phone displays this prompt:

Keep network cfg? 1 = yes 2 = no

In order to maintain the current network configuration settings for the phone when the phone resets, press 1. In order to reset the network configuration settings when the phone resets, press 2.

If you press another key or do not respond to this prompt within 60 seconds, the phone continues with its normal startup process and does not reset. Otherwise, the phone goes through the factory reset process

From this document:

http://www.cisco.com/en/US/products/hw/phones/ps379/products_tech_note09186a00800941bb.shtml#pass

Hope this helps. If so, please rate the post.

Brandon