What should be included in the disaster recovery planning process for a telephone system?
Assuming the phone system in question is either an older time-division multiplexing, or TDM, switch or a smaller "key" or "hybrid" type of system that supports fewer than 30 stations, the most important piece of information is whom to contact at the system vendor or third-party switch maintenance firm.
Older systems may no longer be supported by their original manufacturers. This is typically done to force users to a more modern, e.g., voice over IP, or VoIP, system. As such, it may be difficult to find usable spare parts, such as circuit boards and phones that fit the system in question. It may also be difficult to find technicians who have been trained to maintain specific systems, especially if they are no longer being manufactured.
Older systems may have different requirements for backup power systems, such as batteries and uninterruptible power systems, or UPS. Ancillary systems, such as call detail recording, or CDR; automatic call distributor, or ACD; and interactive voice response, or IVR, systems may be unique to the system installed and therefore may be difficult to maintain.
Your disaster recovery planning process must address these important items in your telephone system:
- Details on network services connecting into the phone system, both for local and long-distance calls, and access to special networks.
- Details on the switching equipment and associated peripherals.
- Requirements for primary and backup power systems.
- Availability and sources of spare parts.
- Backup copies of the switch's operating system and database of station and switching features.
- Documentation that describes system operations and features, as well as how to activate or cancel them and how to troubleshoot problems.
- System maintenance and repair organizations.
- Sources of the parts and supplies that operate with the system.
The last item can often be addressed through what is called the secondary market for telecom equipment, which includes dozens of firms that stock parts and supplies for current production systems, but more importantly, for systems that are no longer in production and/or are no longer actively supported by their manufacturers. Some firms supply parts for a variety of manufacturers and systems, while others specialize in one or two brands (e.g., Avaya and Northern Telecom). These organizations are also a good source of technicians who specialize in maintaining the systems in question.
Your DR planning process must also include these tasks:
From a networking perspective, identify service routing options from local telephone companies. These call diversion options can quickly route incoming calls on the main phone number to an alternate number in case the phone system is suddenly disabled.
Conduct a periodic DR test of the system as part of your disaster recovery planning process, typically by powering off the system and then turning it back on to see if everything reboots properly.
See if the system supports power-failure transfer lines, which automatically connect outside lines to designated stations for temporary service in a power outage. This is an often-unused feature that can be valuable in a power outage.
Keep a supply of spare circuit boards for stations, trunks and common control equipment. Rotate the station and trunk circuit boards in the switch to ensure they are working properly.
Make sure that you have all the available service bulletins for technical troubleshooting.
Keep the room where the equipment is located locked and secured; limit access to the room only to authorized technicians. Keep backup copies of system documentation in a secure area not in the same building as the system.
Periodically inspect wiring from the service-entry area to the main wire frame and to various cable distribution points in your building. Test your backup power systems at least monthly.
Dig Deeper on Disaster recovery facilities - operations
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