Call Log - Longer History?

[WitnessX]

One of the nice surprises of exploring the Titan after unboxing was the Call Log. It was tied in to the Contacts, so it was always nice to be able to know when was the last time I spoke with that person. After a month or so, or after a certain amount of calls, the log gets trimmed. I'm not sure if its based on date, or by count. In either case, would anyone here know how to extend its trimming parameters? I poked around the registry for clues, but haven't found anything that worked. Thanks in advance!