- How To: Place a call on hold on D2
- How To: Setup Grandstream 21XX Series Custom Wallpaper
- How To: Setup Multicast Paging on D2
- How To: Update the Time Display (GXP 21XX Series Phones)
- How To: Use the Intercom
- Park a Call
- Perform a Blind Transfer
- Perform a Directed Call Pickup
- Perform an Attended Transfer
- Updating Grandstream Firmware
- What Is: Do Not Disturb (DND) mode