If CLI is enabled on your line but the calling number is ***** displaying on your phone, then the problem is likely to be with the wiring or setup.
Try testing your Siemens gigaset phone on someone else's line first to confirm it is working ok.
If it is, then the problem is definitely with your own setup - even though it worked ok for the technician, there may not be enough power in the line for the number to display on your Siemens gigaset phone.
Try disconnecting any other equipment that is connected (e.g. broadband router, fax machine, etc) and try again.
If you are using any phone line extensions, disconnect them and connect the Siemens gigaset system directly to the master phone socket.