is there an app to increase the recents call list on the iPhone 4

I am trying to increase to number of recent calls that the iPhone keeps track of. I have searched everywhere I know where to search but cannot find out what the limitations are on the recent call list. I even called Apple support yesterday, and they said their technical manual did not give them what the “limitation” is. I even asked them if there was an app for that, and they could not answer me. I usually make or received at least 90 calls a day, and I can remember my old Sprint phone had well over 4 months of recent call activity.

I am using an iPhone 4 with iOS 4.0.1 with ATT as my wireless carrier in the US, if that makes a difference.

Any help would be greatly appreciated.