• Server Side - DND is managed and maintained on the PBX. When the phone toggles on DND it tells the PBX to toggle on the sever side so both the phone and PBX both have DND enabled.  The downside to this is if you have more than 1 device connected to the same extension if 1 device enables DND all devices will have DND enabled since its server side extension level DND.  The added benefit with it being Server Side DND is if you enable DND with a feature code on the PBX or through User Control Panel the phone will also show it is in DND.
  
  
• Phone Side - DND is on the Phone itself only. The PBX is not aware the phone is in DND and the PBX will send calls to the phone and the phone will than report back to the PBX its busy and not accept the call. This causes the PBX not to be made aware that a device is in DND and that your PBX routes calls to it still only for them to be reject.  The most common reason for using Phone Side DND is if you have multiple devices all for the same extension and you want some devices to be in DND and others not to be.  

Setting Phone Side or Server Side DND

• From within the Clearly Devices module on your PBX you will navigate to the template you want to make this change from from the right menu.
  
  
• Click on the Phone Settings tab at the top
  
  
• Toggle the DND Type option between Phone and Server Controlled
  
  
• Submit your changes.  The module will now rebuild all configs that are using that template and update the phones.