. Call Accounting is usually PC-based. It accepts the call information from the PBX. It then assigns a cost to each call that approximates the true cost of the call and sorts the calls by extension number. The costs for each extension may also be grouped into department reports, often provided to each depart- ment manager. Calls may also be sorted by account codes, numbers associ- ated with certain clients or projects of the company. Thus, a law firm will know how much is being spent on each client and may use the information for billing call charges back to the client. Under these circumstances, the PBX requires the dialing of an account code before each outgoing call is made. The PBX keeps the account code associated with the call and sends this informa- tion to the buffer device. The Telecom Handbook - 51 THE PBX Traffic Study Most PBXs provide information on how the outside lines in the system are being used (call volume on each outside line). This is called a traffic study. Although the call accounting sys- tem is capable of providing a traffic study, it is not always set up to do SO. Instead, the telephone installation and maintenance com- pany is customarily called upon to poll the PBX for a period of time, often a week, to provide the traffic information. When re- questing a traffic study, it is important to be very specific about the information you want and what your objective is. You may have had a new telephone system installed with 20 outside lines for which you are paying $30 each per month (20 X $30. = $600). Now it's a year later and you want to find out if you really need all of those lines. A traffic study runs for one week and tracks all incoming and outgoing calls. The results indicate that at the busiest times of the day, no more than 10 of the lines are ever in use. Being conservative, you decide to leave 15 lines in place and remove the other 5 (5 X $30 = $150), thus saving your company $150 per month. Note: When you remove outside lines, remind your telephone installation and maintenance c