e diagnostics and configuration. The second method is far superior, because it eliminates switching A management system monitor displays information either textually back to a faulty line and avoids using the back up circuit any longer or as dynamic graphical information, whilst hard copy output tends than necessary. Ideally a visual indication of this back up mode is to be limited and textual only. Largely proprietary, these systems lag desirable to avoid excessive call charges generated by a consistently behind in terms of open systems standards compliance as vendors poor leased line service. development budgets focus on local area network management. 39.5.2.10 Speed conversion flow control 39.5.2.15 Security Increasingly included in the feature list is the ability to automat- A rapidly developing market as companies provide increasing ac- ically cater for communicating devices operating at different cess to their networks from either the high street outlet or direct to speeds, essential for modem pool applications where a host com- the customer, modem security is typically delivered as a basic puter running at a fixed speed is accessed by a multi speed environ- password system which can be optionally combined with a dialback ment. facility. On connection the called modem requests a password. If the password is validated by the modems directory, it will disconnect the line and redial outwards to the telephone number associated with 39.5.2.11 Visual audio indications it in memory. Once reconnected, the password is again requested. If successful the user is connected to the service. Modem security is To allow a simple and instantaneous check on status, front panel often integrated within a management system and may be sup- indications are typically provided for transmit, receive, carrier de- plemented by modem identification codes. tect, terminal ready, off hook and power on signals. This is increas- ingly complemented by an internal speaker which monitors the call set up tones. 39.6 Applications The introduction