The 
Conversation History gadget displays details of calls all you have made, received and missed. The gadget also displays the history of the conversations with other contacts. You can use the call log to make a call, add the caller's details to your Personal Directory or search IM conversation.
The call log shown is stored on the telephone system as part of your user settings. Up to 30 records are stored, with new records replacing the old ones when the limit is reached. However, for repeated call records to or from the same number, the existing record is updated and the number of calls count included in the record is increased.
For incoming call, by default, only personal calls (non hunt group) to the user that were answered by the user or which went unanswered anywhere are included in the call log.
•Missed Calls
Calls that you do not answer but are answered by voicemail or a covering extension are not normally logged as missed calls. However, your telephone system administrator can configure the logging of missed calls.
•Missed Hunt Group Calls
By default, only hunt group calls that you answer are logged. However, your telephone system administrator can configure your call log to include missed hunt group calls for selected hunt groups.
•Automatic Deletion
Old call records are automatically deleted when the call log capacity is reached and a new call record needs to be added. In addition, the telephone system administrator can configure the telephone system to delete log entries after a set period.
The Phone Call Log
If you are using an Avaya phone (1400, 1600, 9500, 9600 or J100 Series) with a Call Log or History button, or an M-Series or T-Series phone, by default the same call log as shown by one-X Portal is also shown on the phone. You can then use and edit your call log from the phone or from one-X Portal. The two will change in parallel.
If you are using any other type of phone that has a call log, it will be a call log stored by the phone itself and so does not match the call log shown in one-X Portal. For example, calls made using the one-X Portal do not appear in the phone's call log and vice versa.
In either case, the one-X call log is limited to displaying 255 records.