An account code is typically used to identify a department, project, or client for charge-back or tracking purposes. An account code can be either forced or optional. When an extension is set up with the forced account code feature, the user must enter an account code before they can dial outside calls
1.After lifting the handset (or while already active on an outside call), press Feature and dial 900.
2.Enter an account code by dialing the account code using the telephone's dial pad.
4.Continue with the call.