Just as a quick note to self..

While configuring an Asterisk PBX that sits behind an ISDN Network Terminator NT1Plus 2B1Q branded Telecom Italia, I noticed that all incoming calls where marked as coming from “Unknown”.  Thanks to mighty Google, I found this valuable official operation manual [ITALIAN] NT1PLUS codes You just have to plug a phone to the line you whish to setup (a1/b1 or a2/b2) then compose: *#65# to check if caller identification is on or off hungup and pickup again to compose as needed: *65# to enable caller identification #65# to disable caller identification Now you may call your PBX and check by yourself that the CallerID will show up on the sip phone display as expected without touching a single line of your Asterisk configuration.