This is a well-documented solution for storing unlimited caller ID phone numbers. The site contains schematics and the software needed to decode and store the data.
Some time ago, I subscribed to the Caller Id service to know who is calling me without being required to pick-up the phone. Unfortunately, my basic caller id display could not memorize enough numbers, and I had to write them manually in a computer to keep them. That’s why I decided to find a way to log the calling numbers directly to my computer. [via]
Caller ID decoder - [Link]