Voice Over IP - UK

Voice over IP - or VoIP - has been around for many years, but with so many ways of implementing the technology, which one is best for your organisation?

Voice over IP is a dream concept that has been a while in the making. The idea of conducting all your telephone calls over the Internet -- and avoiding high long distance charges in the process -- is an attractive one for any budget-conscious manager. However, quality and reliability have been big problems for IP phone services in the past, and the need for compatible software on both ends of the conversation kept many from investing in the products for a long time.

Today, better Voice over IP products are addressing and solving these problems. This article discusses some of the more popular Voice over IP products and services and how the technology can save money for your business.

What is Voice over IP and why should you care?
The Internet protocol (IP) was originally designed for sending data packets. Voice over IP involves sending spoken conversations, in real time, over an IP network. A regular phone line transmits voice as analogue signals, but to be sent over the Internet (or a TCP/IP-based private network), an extra step is added. Sound is converted to analogue signals, then digitised (converted from analogue to digital) and then transmitted over the network. At the receiving end, the conversion process is done in reverse.
Voice over IP is part of a larger technology category, IP telephony, which encompasses transmission of FAX, video, and any other form of data traditionally transmitted over the public switched telephone network (PSTN). The idea of IP telephony is itself part of a larger trend toward convergence of computer, telephone, television, security monitoring, lighting automation, and related technologies.
Advantages of Voice over IP over public telephone service
PSTN has worked fine for transmitting voice for many decades -- so if it's not broken, why fix it? The compelling factor behind Voice over IP is a practical one: cost. Long distance charges can cost businesses hundreds or thousands of pounds per month. If the business has a fixed cost (unlimited access connection to the Internet) calls transmitted over that connection can be effectively free. Some Voice over IP services do charge a monthly fee, but it is typically far less than Telco charges for long distance.
Disadvantages of Voice over IP
Given the cost advantage, why haven't all businesses rushed to abandon the public telephone network? Why aren't all long distance calls being made over IP? As with any business decision, there are tradeoffs. Some of the disadvantages of using Internet technology for all of your voice calls include:
Initial setup cost: Although there are low cost and even no-cost ways to transmit voice over IP, an enterprise level company serious about Voice Over IP will have to invest heavily in one or more Voice Over IP devices (such as one of Cisco's voice gateways).
Quality issues: Although it is getting better all the time, the quality of most Voice Over IP services and products can't yet match that of PSTN. There are inherent challenges in sending a voice stream over a packet network.
Incompatibility issues: Some services require that both the caller and the called party be subscribers to their service, and some software programs require that both parties have the same software installed. However, there are other services/programs that allow you to call anyone, including calling from your computer to a regular telephone, or even calling from phone to phone with packets routed over IP in between.

Weighing the pros and cons
Despite these disadvantages, Voice Over IP can still be a viable alternative to PSTN -- if you do your homework before committing to a particular product and service. I recommend that you run a pilot program first, testing Voice Over IP with a small group of users, before rolling out a Voice Over IP solution to the entire company. You may want to test several different products and/or services before making a decision. You should also evaluate your workers' telephony needs. You may find that the best solution is to switch some departments or selected users to Voice Over IP while others continue to rely on PSTN for their telephonic needs.

Voice Over IP in a nutshell
Voice over IP can be hardware or software-based. The earliest products worked exclusively via software, and users at both ends of the connection needed a computer running the software, an Internet connection, a sound card, and microphone. The connection was often only half duplex, making the conversational experience more like talking on a two-way radio than on a telephone.

There are still many software-based Voice Over IP products in use, and these tend to be less expensive than other Voice Over IP solutions. Voice Over IP can also be implemented using gateway devices. These are dedicated hardware devices that create a bridge between analogue telephony equipment (phones, fax machines) and the IP network using one or more of the Voice Over IP protocols. A third option is to subscribe to a Voice Over IP service offered by an IP service provider.
Voice Over IP protocols and standards
Standards and protocols are necessary for devices to communicate with one another. The protocols used by Voice Over IP include:
H.323
Session Initiation Protocol (SIP)
H.323 is a standard that was developed by the International Telecommunication Union (ITU), which includes a group of protocols used for Voice Over IP , video conferencing, and sharing data. These include protocols that manage call setup and termination, negotiate channel usage, and handle authentication and security. Most major Voice Over IP product vendors, such as Alcatel and Cisco, make products that rely on H.323.
For more information about H.323 check the IMTC Web site.
SIP is a newer, less complicated protocol that was designed specifically for Voice Over IP . The Internet Engineering Task Force (IETF) developed SIP as an alternative to H.323.
Microsoft includes a SIP stack in Windows XP that is used for real time voice communications by Windows Messenger. Many vendors, including Cisco, market SIP-based phones. Click here for more information about SIP.
Some vendors use proprietary Voice Over IP protocols for their devices. In addition to its SIP products, Cisco developed a protocol of its own called Skinny, which it licensed to other vendors. Protocols can be (and often are) used in combination; for instance, SIP can be used between the phone and the gateway while H.323 is used between the gateway and the PSTN. Another protocol, the Media Gateway Control Protocol (MGCP) can be used by SIP to create a gateway to the PSTN.
Tip
In selecting which Voice Over IP product to use, you need to consider compatibility with your firewall or NAT product. For example, Microsoft's ISA Server 2000 supports the H.323 gateway, but does not support SIP.
Voice Over IP products and services
There are a large number of Voice Over IP software programs, Voice Over IP -enabled hardware devices, and Voice Over IP services available. Which type of Voice Over IP solution you choose depends on the call quality you need, the amount of Voice Over IP traffic, and how much control you want to have over the technology.
Voice Over IP software products
Voice Over IP software programs range from free to very expensive. NetMeeting, which is included with Windows 2000 and XP, is an H.323-based voice and video conferencing program. Windows XP also includes SIP-based Windows Messenger. Both come with the operating systems.
Medium-priced software phone products include eStara's SIP-based SoftPhone or Smith Micro's H.323-based VideoLink Pro. PocketGphone is Voice Over IP software for your Pocket PC2002 PDA. Enterprise-level products include VocalTec's Essentra SIP Server.
Tip
NetMeeting is "hidden" in Windows XP; you won't find it in the Start program menus. To open it for the first time, you must type conf at the Run box. When you set it up, you'll be given the option to put an icon on the desktop or in the Quick Launch bar.
Software solutions are generally less costly than dedicated hardware solutions, and many are available in free trial versions, so you can evaluate them before incurring any cost.
Voice Over IP services
Services, like software, run the gamut when it comes to cost. Free services, such as PhoneFree, which allows you to make free PC-to-PC audio or video calls, are geared toward consumers and often don't work behind a firewall.

There are a large number of companies offering business-grade Voice Over IP services, such as ICG's VoicePipe. Another player, Vonage, offers both residential and small business plans with unlimited domestic long distance for $39.99 (£25) per month and low per-minute international rates. You will typically need special software and/or hardware, provided by the service provider, to use these services.
A Voice Over IP service generally allows you to forego the steep upfront cost of investing in professional-grade software or hardware products, and since some services are available on a free trial basis, you can try them without risk. Using a service might be preferable if you don't have the onsite technical personnel to maintain hardware or troubleshoot software problems.
Voice Over IP hardware devices
Hardware solutions tend to be the most costly way to implement Voice Over IP , but they are often easier to configure than software solutions, and owning the hardware allows you more control than subscribing to an outside service. Voice Over IP hardware devices generally include:
· Analog-to-digital phone converters such as the Cisco ATA 186. You plug a standard telephone into the adapter and its analogue signals are digitised for transmission over IP.
· Integrated IP phones, such as Nortel's 12004 Internet Telephone, Cisco's large line of IP phones, and Adtech's SI-160 IP Phone, which includes a smart card reader for added security.
· Gateway devices, such as those developed by RADirect, which use a transport technology called TDM over IP to extend T1 and T3 transmissions across IP networks; MultiTech's MultiVOICE OVER IP gateways, which support both SIP and H.323; and Cisco's carrier-class VOICE OVER IP and Voice over ATM (VoATM) MGX 8000 Series Gateways.

Some hardware devices may also require that special software be installed on the network (for example, many of Cisco's Voice Over IP products require that Cisco's Call Manager software be installed). Many of the hardware devices are compatible with various Voice Over IP services.
Tip
In addition to dedicated Voice Over IP devices, some routers -- such as the Cisco 3600 series -- can be configured to transmit voice over the IP network.
Some devices do not require a computer on either end. For example, D-Link's i2eye video phone transmits both voice and video over a DSL or cable connection when you plug the device into a standard telephone and TV, using the H.323 standards (you need the same setup on both ends).
More improvements to come
Voice over IP is finally coming into its own. As transmission quality and reliability improve, managers should recognise the significant cost savings of using their Internet connections and IP-based LANs for voice communication instead of paying high Telco charges. The future promises more improvements, with newer, easier-to-use protocols such as SIP and wireless Voice Over IP already gaining ground.
However, it's not easy to choose from all the Voice Over IP solutions that are available -- and the situation promises to only get more difficult in the future as more and more software companies, hardware vendors, and service providers jump into the game.

Many thanks to Deb Shinder of TechRepublic.com for this article