# SMDR - Call Timing

Trunk call timing aspects (for example, call start time), form one of the prime function areas of the SMDR feature. Accuracy in recording call timing is essential in order to avoid false system analysis and incorrect accounting. One safeguard against false time records is the Time Change Reporting option. This option, when selected, causes two time stamps to be printed when the system clock is changed. The first indicates the time and date immediately prior to the change, and the second indicates the time and date immediately after the change. The format for the time stamp record is shown in the example below. The system clock can be set by maintenance personnel or by an attendant at any time.