Grandstream IP PBX UCM – Completion Request / Busy Camp-On

Grandstream Call Completion Busy Camp on


This article illustrates the scenario when the caller requests Call Completion when called party is busy with Grandstream IP PBX UCM6XXX. You may refer to the complete guide here.

By default, when the Call Waiting feature is disabled at the Extensions and IP Phones, the Call Completion request works only on unanswered or timeout calls. Also, the caller has to make sure the call is ended properly by having the busy tone play until FINISHED to request Call Completion successfully.

Call Flow

1. Create 2 extensions A and B in UCM

2. At UCM’s UI > Extensions > Features > 
– Disable Call Waiting 
– Enable CC at Normal mode

3. Make sure the Call Waiting feature is also disabled on physical IP Phones

4. Ext. A dials ext. B

5. Ext. B is busy and does not answer. The ringing is timed out.

6. At this time, A will hear the busy prompt ‘Ext B is not answering the call, please try again……’ 

7. Please wait for the busy tone plays until finished and the phone goes back to the idle call screen.

6. Now, Ext. A dials *11 to request Call Completion and hear the prompt ‘Call completion request successfully.”