Description
Call forward makes the remote working solutions more efficient and ensures continuity of business operation. This article describes the settings required to allow the forwarding of the original Caller ID of external numbers in Grandstream IP PBX UCM.
1. Make sure that the UCM has the latest firmware version
2. Make sure the following settings are:
a. Remove the PPI or PAI headers under Trunk > Advanced Settings
b. Enable “Trust remote party ID” under PBX Setting > SIP Settings > ToS
c. Enable “Send remote party ID” under PBX Setting > SIP Settings > ToS
d. Disable “Enable Division Header” under SIP Settings
c. Uncheck “Keep Trunk CID” and enable “Keep Original CID” under Trunk Settings
d. Ensure that CallerID Number is left blank under Extension > Basic Settings (optional)
No audio when UCM forwards the call to external numbers
Try these: PBX Settings > SIP Settings > ToS > RTP Keep-Alive: set to 1