UPS IN A CONVERGED VOICE AND DATA ENVIRONMENT

The evolution of the Internet during the last 40 or so years has dramatically changed the way in which both individuals and organisations view their means of communication. Personal computers have become virtually standard for businesses, with home use continually increasing, so that nowadays communication by e-mail is in many circumstances the preferred option. Networking that enables multiple workstations to access as well as add to and amend information held in databases has also become a standard for businesses and the exchange of data files as attachments to e-mails is commonplace.

Fundamental to this evolution and developing at approximately the same pace, was the introduction of digital technology into the originally analog telephone network. In essence, this enabled the creation of a digital network within the existing analog system, using the same telephone wiring being used for the analog lines. This, for example, enabled data to be sent at high speed between two business computers linked to the digital network, with any analog voice message between the two operators travelling telephone to telephone down the same wiring. With the advent of Broadband technology accellerating the use of the Internet as a medium for transmitting data, it was inevitable that there would be a challenge to the telephone as the principal electronic means of communicating by voice.

Voice over Internet Protocol (VoIP) duly arrived. Crucially, VoIP services interface with the Public Service Telephone Network (PSTN) to establish a Voice Gateway to enable both outgoing and incoming calls to be prepared for their journey, whether this be via the Internet, private network or PSTN, and for their destination, be this a PC, telephone or other device or accessory.

In simple terms, the voice message is broken down into data packets and compressed for its journey through the Internet and is decompressed and reassembled for its journey through the PSTN. By converting voice in to data, VoIP technology opens up the possibility of transmitting that data via an existing businesses data network, enabling the creation if a converged IP telephone and data network.

The fact that these services are available is not in itself sufficient to convince businesses that this technology should automatically be introduced. Other factors would need to be taken into account such as flexibility, cost-effectiveness and, perhaps most important of all, reliability. Recent surveys of business planned development suggest that in Europe 33% of respondents intend to implement a VoIP system in a year or two and that worldwide some 40% intend to do so. With VoIP systems clearly on the agenda of many businesses, a timely reminder of the importance of one special factor will not be out of place the importance of consistent, good quality power.
The telephone is, perhaps, seen as the most reliable of electrical services. If all else fails, it is generally still possible to make telephone calls. However, an Internet Protocol (IP) telephone system relies on the mains power supply and the IP system will experience the same interferance that affects other electrical equipment during a mains power aberration or failure. The value of Uninterruptible Power Supply (UPS) devices, providing high-availability power protection for electrical equipment and systems, has been understood by businesses for many years, but any existing arrangements will need to be looked at again if an IP system is introduced, particularly if it is to be merged with an existing data network. Of paramount importance to the business will be the highest possible availabilty of the IP telephone system, which is its portal to customers and the outside world.

The same degree of availability may not necessarily be demanded of the data or process systems operated by the business. Although a hinderence, it may be acceptable for the business to be without its systems during any failure in the power supply, provided that those systems are not damaged if the power fails. This defensive reaction to a power outage or anomoly can be provided by a line-interactive UPS that regulates the input voltage feeding the business systems and corrects inequalities within a set supression range. In the event of a power fluctuation outside that range or of a complete power failure, the UPS provides enough battery back-up time, generally 10 or 20 minutes, to enable orderly system shutdown. This level of power protection would not be acceptable for an IP telephone system in a converged environment.

If the business operates mission-critical systems the existing UPS back-up will normally have the more sophisticated double conversion on-line topology. The input power is constantly conditioned and regenerated, which eliminates aberrattions and distortions. In the event of a total power failure the UPS will provide battery power to support the critical load until either power is restored or the UPS batteries run low, in which case a controlled system shut down will take place. Although the extendable battery back-up time may cover a power failure lasting several hours, cover for the serious long-term power failures that can occur may be provided by a generator. When determining the UPS architecture that is to be used for the converged network, the needs of the IP telephone system will be the decisive factor.

Generally speaking, if there is an existing data network there will be a data control centre of some sort, possibly with on-line UPS protection that may be sized to include the additional requirements of the IP telephone system. However, any remote distribution hub included in the network may not have the correct UPS cover. Care must be taken to ensure that UPS back-up in such locations is adequate, even if no additional IP telephone system hardware such as a Voice Gateway is being installed at the location. Any existing line-interactive UPS cover must be replaced with full on-line UPS protection, with back-up time to match the cover provided centrally at the data control centre. All the critical components of the IP telephone system will need on-line UPS protection to an equal extent to ensure the maximum operation of the full system. This includes not only hardware such as Powered Switches and the Voice Gateways that are essential to the operation of a VoIP system, but also the PCs or handsets through which voice message are to be sent or received.

In this context, it is now possible through Power over Ethernet (PoE) to transmit power as well as data over a single ethernet cable. At the moment the approved standards restrict the power of the current that can be transmitted, but even so it is possible to use PoE to power IP telephones over an existing LAN cabling infrastructure. Such an arrangement may enable the power protection of all the telephones on the LAN with one UPS.

There will be further matters outside power protection that will need to be considered. IP telephone equipment will generally need to operate in a controlled environment, which may mean that existing specialist air conditioning arrangements will need to be reviewed, particularly at remote hubs and locations. Monitoring will also be a key factor. Ideally, every item of environmental and power control equipment should carry communications sotware linked to a web-based monitoring and management system to ensure that any actual or potential problem can be dealt with. High precision air conditioning and power protection equipment will require maintenance and the equipment provider should be looked upon to offer rapid response maintenance arrangements.