How can I enable Caller Identification on Ericsson DIALOG 4187 plus?

I have purchased the Ericsson DIALOG 4187+ Analogue phone (currently marketed by Aastra). When I connect this to an analogue telephone line (which also serves ADSL connectivity for broadband) I do not see the incoming CLI number. What could be the issue? Is there any additional device that needs to be added to the phone for enabling CLI? I am currently using this phone in India.