Power and convergence

The evolution of the Internet has dramatically changed the way in which organisations view their means of communication. Personal computers have become virtually standard for businesses, with home use continually increasing, and 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 e-mail attachments is commonplace.

Fundamental to this evolution, and developing at around the same pace, was the introduction of digital technology into the telephone network. This enabled the creation of a digital network within the existing analogue system, using the same telephone wiring. This, for example, enabled data to be sent at high speed between two business computers linked to the digital network, with any analogue voice message between the two operators travelling telephone to telephone down the same wiring.

With the advent of broadband technology accelerating 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.

The Internet age

Crucially, VoIP services interface with the public switched telephone network (pstn) to establish a voice gateway. This enables 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.

In simple terms, the voice message is broken down into data packets and compressed for its journey through the Internet then is decompressed and reassembled to pass through the pstn. By converting voice into data, VoIP technology opens up the possibility of transmitting that data via an existing businesses data network, enabling the creation of 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 importantly, reliability.

Recent surveys of businesses’ planned development show that 33% of respondents in Europe intend to implement a VoIP system in a year or two; worldwide some 40% intend to install such a system. 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 – consistent, good quality power.

Making calls

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 will experience the same interference 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. However, any existing arrangements will need to be re-examined 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 availability 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 hindrance, it may be acceptable for the business to be without its systems during any failure in the power supply, provided that they are not damaged if the power fails. This defensive reaction to a power outage or anomaly can be provided by a line-interactive ups that regulates the input voltage feeding the business systems and corrects inequalities within a set suppression 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.

Critical missions

If the business operates mission-critical systems the existing ups back-up will normally have the more sophisticated double-conversion online topology. The input power is constantly conditioned and regenerated, which eliminates aberrations and distortions.

In a total power failure the ups will support the critical load until power is restored or the ups batteries run low, in which case a controlled system shutdown will take place. Although the battery back-up may cover a failure lasting several hours, protection for serious long-term failures may be provided by a generator. When determining the ups architecture for the converged network, the needs of the IP telephone system will be the decisive factor.

In general, if there is an existing data network there will be a data control centre, possibly with online ups protection that may be sized to include the additional needs of the IP telephone system. 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 online 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 online ups protection to an equal extent to ensure the maximum operation of the full system. This includes hardware such as powered switches and the voice gateways that are essential to the operation of a VoIP system, plus the pcs or handsets through which voice messages are to be sent or received.

It is now possible through Power over Ethernet (PoE) to transmit power and data over a single Ethernet cable. The approved standards restrict the power of the current that can be transmitted, but 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 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 software linked to a web-based monitoring and management system to ensure that it is possible to deal with any actual or potential problem. 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.