From: Microsoft Communities on
Look here:

This sample is a Call Log Reader using the .NET CF:

http://www.microsoft.com/DOWNLOADS/details.aspx?familyid=C0BD7407-FE20-41F7-98B9-72D54F78F88A&displaylang=en

If you want an intro to storing data in a MSSQL database using ADO.NET then
check my blog, it gives a quick rundown of the key classes (Note that the
Compact Framework / SQL CE is a little different) :

http://www.jamesben.net/?p=67

And it also covers using PocketOutlook (Which may be useful to actually
match contact names to the numbers in the log)

http://www.jamesben.net/?p=6