On the 4K, In Assistant, on the Basic3 tab, there is a parameter for Call Logging that defaults to "not any". If the phone is an Openstage phone or other phone with a display, change that to "all". Also note there is a DIMSU parameter that determines the maximum number of call logs the system can hold. Sorry, I don't know which AMO the "call log" setting is under, but if you are insto AMOs you could try SDAT and see if it's there.
If you have an OS60 the call log has a dedicated button right on the phone; If you have an OS40 with newer firmware you can access the call log through the menu. If set to "all" the system will report recently received calls (taken), missed calls, and dialed calls. You can clear the log if desired.
If you want to do historical research and broad scale inquiries into call volumes and the like, as sbcsu stated above, the systems have CDR capability - which does require some setup. If that is your goal I strongly recommend a product called Traffic Analyst made by Impact Technologies. Product cost is partially based on how many total ports in use your system has, but you can find out stuff you never dreamed of - some serious big brother stuff!!
Don Bruechert, Voice Comm Analyst II
CareTech Solutions @ Holy Family Memorial
Manitowoc, WI, USA