Hi @adon_bradshaw
What is the make and model number of the phone?
Have you got a Caller ID feature on your phone service?
Only asking as usually for landline services, Caller ID is a subscription service and is not automatically connected to the service unless asked for and paid for by the account holder of the phone service.
If you haven't got Caller ID showing as an item in your phone bill then most probably you haven't got it as a feature on your phone service.
If you have got it and it doesn't work, contact your phone service provider and verify that the Caller ID facility has been enabled on your service.