If you have a base unit not using the gateway module this is how to turn it off: (if not it gives out DHCP…)
Using the buttons on the LCD panel:
1. Press and hold [Enter] button until the display show ?LINE MODULE 1?
2. Press [Down] button 2 times until it show ?SECURITY GATEWAY?
3. Press [Enter] button
4. Press [Down] button 2 times until it show ?SG MODULE ENABLE?
5. Press [Right] button to change enable to disable
6. Press and hold the [Enter] button until it show ?SYSTEM REBOOTING??
Note: This may not be current, it is from my 2010 notes archives…