Log in to the 3CX Management Console
Select "SIP Trunks" from the 3CX Dashboard.
Edit or double click the SIP Trunk you are adding the number to.
Click on the "DIDs" tab at the top, then click on the "+ Add Single DID" button.
Enter the DID number and click off the number box or select "+ Add Single DID" to add another number.
By default, Voxtelesys formats the number in 10 digits, but can support +1 or any prefix. Set up the prefix in our Portal.