Caller ID detection from landline or from LCD display using Arduino.

I need a landline caller ID detection and record system using arduino. When a phone call comes to the telephone line, I need arduino to know the phone number of the caller and store it to the SD card. There are two ways in which I think this can be done: 1) In a normal telephone: By using an IC that can decode this information and send it to arduino. 2) In a telephone with a caller ID functionality: By intercepting the signal going to the LCD display which contains the phone number, and interpreting it using arduino. Any cheap, non-destructive, and innovative solution is welcome. The system needs to be well documented. This is going to be a part of a larger project where there is audio recording/playing initiated after answering a phone call. I already have the other parts of the project completed, but I need the caller ID to be detected and stored in the SD card to finalize the project. You'll obviously need a phone for testing, I used Geepas Telephone GTP 7185 (which has caller ID feature). It's prefered to use this phone, or at least another similar easily-available cheap phone. If you're going to use this phone, I'm willing to pay for its cost. Willing to pay more for fast and well documented work. You should also know that this will lead to further long-term paid collaboration.