Fixed line communications for the future?

15 June 2007

Voice over Internet Protocol, or VoIP, is set to revolutionize the way that businesses communicate internally and externally.

A bit of background

Traditionally, voice telecommunications for business have involved the caller dialling from a handset, with the call being routed by a PABX (Private Automatic Branch eXchange or telephone "system") onto the public switched telephone network (PSTN) to the BT local telephone exchange. The PSTN is a circuit switched network which establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. Each circuit that is dedicated cannot be used by other callers until the circuit is released and a new connection is set up. In contrast, the Internet Protocol network (IP network) is a packet switched network which splits traffic data (for instance, digital representation of sound, or computer data) into chunks, called packets, that are routed over a shared network. Packet switching networks do not require a circuit to be established and allow many pairs of nodes to communicate almost simultaneously over the same channel. Each packet is individually addressed precluding the need for a dedicated path to help the packet find its way to its destination.

The future (and maybe the present too…)

Increasingly, BT are using a packet switched network, their 21st Century Network (or 21CN) to carry calls between their local exchanges. By 2008 BT plans that 50% of all calls carried will use this network. The majority of public and private sector organisations already own and maintain two of their own communication networks; one for voice and a completely separate one for data. Voice and data convergence is the process of combining these networks into a single, IP based network which can carry voice "packets" and data "packets" at the same time. Data traffic is relatively tolerant to being split into packets to be moved around a network and then put back together when it reaches its destination, and it doesn't particularly matter that all the packets arrive in the right order at the same time. However, if voice packets arrive in the wrong order, or at the wrong time, the resulting sound would probably be unrecognisable as speech. For this reason voice there has to be a system of prioritising voice packets over data packets, and ensuring that they arrive at their destination in the right order and at the correct time. This system is typically referred to as Quality of Service (or QoS). Voice over Internet Protocol, also called VoIP, IP Telephony, Internet telephony, Broadband telephony, Broadband Phone and Voice over Broadband is the routing of voice conversations over the Internet or through any other IP-based network. Having established, in very simple terms, the basic technology let's now take a look at some of the pros and cons…

The Benefits

VoIP can facilitate tasks that may be more difficult to achieve using traditional networks:

Ability to transmit more than one telephone call down the same broadband-connected telephone line. This can make VoIP a simple way to add an extra telephone line to a home or office.
Incoming phone calls can be automatically routed to your VoIP phone, regardless of where you are connected to the network. Take your VoIP phone with you on a trip, and wherever you connect to the Internet, you can receive incoming calls.
Free phone numbers for use with VoIP are available in the USA, UK and other countries from organizations such as VoIP User.
Call center agents using VoIP phones can work from anywhere with a sufficiently fast and stable Internet connection.
Many VoIP packages include PSTN features that most telecommunication companies normally charge extra for, or may be unavailable from your local telephone company, such as 3-way calling, call forwarding, automatic redial, and caller ID.
VoIP is location independent, only an internet connection is needed to get a connection to a VoIP provider.
VoIP phones can integrate with other services available over the Internet, including video conversation, message or data file exchange in parallel with the conversation, audio conferencing, managing address books and passing information about whether others (e.g. friends or colleagues) are available online to interested parties.
Reduced outbound call costs, typically 0.4 to 0.7p per minute compared with 1.0 to 1.4p per minute for standard PSTN carried calls.
Free calls between VoIP enabled sites (if using similar systems).
Only one communications network to manage and maintain.

Potential pitfalls

Broadband bandwidth - all VoIP systems rely on the availability of reliable bandwidth. It is therefore essential that your choice of broadband provider is very carefully considered. A provider that is offering "free" bandwidth or "low cost internet when you buy your [insert as appropriate] from us" should probably be avoided if your are planning a VoIP rollout.
Power outages - Conventional phones are connected directly to telephone company phone lines, which in the event of a power failure are kept functioning by back-up generators or batteries located at the telephone exchange. However, household VoIP hardware uses broadband modems and other equipment powered by household electricity, which may be subject to outages dictating the use of an uninterruptible power supply or generator to ensure availability during power outages. Early adopters of VoIP may also be users of other phone equipment, such as PBX and cordless phone bases, that rely on power not provided by the telephone company. Even with local power still available, the broadband carrier itself may experience outages as well. While the PSTN has been matured over decades and is typically extremely reliable, most broadband networks are less than 10 years old, and even the best are still subject to intermittent outages.
Data network failures - if your data network fails not only will email stop working, but your telephones will also cease to operate. Consider how robust your data network is…
Emergency calls - The nature of IP makes it difficult to locate network users geographically. Emergency calls, therefore, cannot easily be routed to a nearby call centre, and are impossible on some VoIP systems. Sometimes, VoIP systems may route emergency calls to a non-emergency phone line at the intended department. Moreover, in the event that the caller is unable to give an address, emergency services may be unable to locate them in any other way. Following the lead of mobile phone operators, several VoIP carriers are already implementing a technical work-around. For instance, one large VoIP carrier requires the registration of the physical address where the VoIP line will be used. When you dial the emergency number for your country, they will route it to the appropriate local system. They also maintain their own emergency call center that will take non-routable emergency calls (made, for example, from a software based service that is not tied to any particular physical location) and then will manually route your call once learning your physical location.
Security - early VoIP systems did not support encryption and, as a result, it was relatively easy to eavesdrop on VoIP calls and even change their content. The latest systems apply IPSec (Internet Protocol Security) encryption to the digitised voice traffic.
Finding the right supplier/partner - probably the biggest mistake made by organisations wishing to realise the benefits of VoIP is during the selection of their service provider. Whilst most in-house ICT departments will have extensive data experience, few unfortunately, will have the necessary expertise to ask the right questions of potential VoIP providers. Similarly, professional purchasing organisations may be highly successful at buying stationery and print cartridges, but are unlikely to possess the technical expertise to select the right potential partners for VoIP. It pays to consult organisations with expert technical knowledge.

For more information please contact Steve Bellerby on 01952 825 820.