telephones, and on the telephones of the groups backing up each of the secretaries. If the telephones are all in place, these changes may all be done from the on-site MAC terminal, without calling in the telephone installation company. It is always advisable to inspect the indi- vidual telephones to be sure that the changes took effect and to change the paper labels which most telephones still use. (Note: Some newer systems enable users to take the telephone with them and plug it in in the new office, retaining all of the extensions and features.) Another example of a PBX change which can be made on- site is that of changing the toll restriction on a telephone. Your call accounting system may indicate that a lot of long distance The Telecom Handbook 53 THE PBX calls are being made from the lunchroom telephone. Since em- ployees are permitted to make local calls only, that telephone is now reprogrammed SO that only calls to the local exchange can be made. All other call attempts will be routed to the switch- board attendant. An advantage of having a MAC terminal on site (and some- one in your company trained to use it) is that it will provide you with current information about how your system is programmed. Otherwise, you may be dependent on your telephone installation company or may even need to collect the information manually. MAC terminals may enable you to obtain the following: A list of all extensions in use in your telephone system. A list of all spare (unused) extensions in your telephone system. A list of all outside lines (trunks) in your telephone system. This will be by the trunk number assigned to each outside line in the PBX. It will not provide the actual telephone num- ber assigned to the line by the local telephone company, although there may be a field for this to be manually entered. A company telephone directory listing name, department and extension number. A list of all extensions with their associated class of service, meaning which areas can be called and which system func- tions can be acc