Question : Change Log on data

I have made a cell phone tracking database.  This tracks down who holds which phone with what number and what are the plans for it.  Is there a way to track changes made to the account of each of these numbers.  Say for example, we hired a new employee of a vacant position and we want to give him a phone that exist on our database.  I want the database to record the changes that was made on it. like when it was given to him or if the device for the phone change, I want to be able to log this.  How can I do this?

Thanks

Answer : Change Log on data

If there is ever a chance that a Cell may be assigned a different phone number, then a table of Cells, with SN as the pk and another table CellHistories with CellHistoryID as the autonumber pk and SN as the foreign key from Cells.  Here you have the complete history of each cell:

CellHistories
========
CellHistoryID - pk - autonumber
SN - fk - serial number from Cells
EmpID - fk - from Employees
CellPlanID - fk - from CellPlans
PhoneNumber - text
TDate - datetime - transaction datetime using Now()