oice over Internet Protocol (VoIP) is a technology that allows your voice to be digitized and transmitted over the Internet, and is an inexpensive way to make both long-distance and local telephone calls. An estimated 5 million people will be using VoIP as their primary telephone service by the end of this year.

Why is VoIP cheaper? Historically, telephone conversations are carried over the Public Switched Telephone Network (PSTN) using a dedicated two-way “circuit” between the parties in a telephone conversation. Because a given pair of wires could only carry a single conversation, long distance calls could be very expensive. In fact, the price of long-distance telephone service has dropped significantly because conversations are usually carried over VoIP networks during part of their transmission.

A VoIP telephone call begins by converting sounds from an analog signal to a digital signal using a process similar to that used to create a CD from a studio recording. The digitized voice information is then separated into packets that traverse the Internet. When the packets reach their destination, they are reassembled into the correct order and the process is reversed, yielding an analog audio signal that the person receiving the call hears.

There are three different ways to make VoIP calls:

1. By using an analog telephone adaptor (ATA). The ATA is a box that provides the hardware and software that allows you to connect a traditional telephone to your Internet connection and, thereby, connect to a VoIP provider. VoIP providers frequently include ATAs with their service.

2. By using an “IP phone.” This device has everything built in that it needs to make an IP call. The IP phone connects to an Ethernet network router, or it may connect using a wireless network (Wi-Fi).

3. The cheapest way to use VoIP is via a computer-to-computer connection, otherwise known as a “softphone.” There is no telephone hardware to buy, and software is either free or very inexpensive. All you need is the VoIP software, a computer, microphone and speakers and an Internet connection. Other than your monthly ISP fee, all calls, both local and long-distance, are free. The downside of computer-to-computer connections is that your call recipient needs to be at their computer and online in order for a call to be placed. There is no answering machine service, either, on the no-cost plan. Service providers such as Skype <www.skype.com>, for example, do allow you to pay a service fee for the ability to connect to a traditional telephone. You also can pay a fee to have answering machine and voicemail services for this type of connection.

VoIP Advantages
The major advantage to VoIP is the consolidation of data and voice transmission into a unified IP network. For service providers, this encourages standardization, simplifies equipment needs, allows further processing of voice data, and improves efficiency, thereby saving money. For end-users, voice communication now has the same range as the Internet or IP network. For a business, its central, branch and home employees can share voice communication networks and resources such as corporate address books and advanced telephony features. For the home user, there can be significant improvement in telephony features as well.

Flexibility
With VoIP, your telephone number travels with your telephone, much like a cellular telephone number does. Generally you can make or receive a telephone call from anywhere in the world that you have broadband Internet access on your own IP phone, ATA or softphone. With WiFi IP phones, you can enjoy this benefit wirelessly.

Some providers allow you to choose the area code for your telephone number or purchase a second “virtual” number (for a fee) in a different area code. This arrangement allows your contacts in that area code to call you using local rates.

Quality
Whereas sound quality of VoIP services was initially inferior to standard telephone services, today its sound quality is equal to or superior to that of traditional telephones.

Price
Some providers, primarily those with computer-to-computer service, offer their services for free. Typically this is only for calls to other subscribers to the service.

Most providers offer minute-rate packages for a monthly fee similar to cellular telephone plans. Most of these plans allow you to call same-service subscribers for free. Some providers charge for a long-distance call outside your calling area much like traditional telephone providers do. Others permit you to call anywhere at a flat rate. Rates are usually less expensive than cellular or traditional telephone plans.

Features
VoIP providers include various features in their subscriptions, many of which are unavailable or cost extra with traditional service providers. These services typically include Caller I.D. With Name, Call Waiting, Call Forwarding, Call Transfer, Three-Way Calling, Repeat Dial and Return Call.

You can check your voicemail via telephone or Web browser. Voicemail also can be sent to you via e-mail (as an attachment), which you can retrieve on your computer or handheld. You can store these files on your computer, e-mail them to someone else or listen to them through your computer’s speakers.

More specialized services often are available, such as giving a list of specific callers a busy signal, playing a “not in service” message or immediately sending a caller to voicemail. These actions occur before your telephone rings and are a handy way to deal with unwanted callers.

VoIP systems also can track your incoming and outgoing call history via your softphone. You may find it easier to search the call history for a recently used number than to look it up in the address book.

Videophones and Teleconferencing
VoIP also provides the ability to videoconference and teleconference without expensive proprietary solutions, as both audio and video streams can be transported over an IP network.

Presence
Presence software can identify — via a network device (e.g., computer, cellular telephone or IP phone) — whether an employee is available, away or working, while also noting how best to contact him/her. In more advanced applications, presence can indicate what project an employee is working on and where he/she is located.

Instant messaging is a good example of simple presence software. You can use this software to have a typed, on-line conversation with any number of different people. You have control over whether others can contact you by setting a status indicator letting them know whether or not you are available.
More powerful presence solutions detect the users automatically and can use logic to identify what they are doing, either by their proximity to other people, or by their usage of network resources such as computers or telephones.

Presence could be very useful in helping to speed communication within an organization or between an organization and its customers. Vocera <www.vocera.com> has a presence solution whereby voice commands allow a hands-free, wireless connection to be established between individual employees or groups of employees. This system does not only respond to human responses, however. In hospitals, alarms from patient monitoring systems, for example, can be routed through these devices and sent to a specific nurse. If this nurse is unavailable, then an alternate nurse or group of nurses could be contacted.

Application Integration
Application integration is the connection of a networked computer and an IP phone via appropriate software such that the computer can interact with the telephone. A simple, yet practical, application is to look up a telephone number from an address book program such as Outlook and then automatically place the call. Many VoIP service providers offer such a software add-on.

Calendar software also can be integrated with a softphone and presence software to manage incoming calls based upon the recipient’s schedule. In this way, telephone calls can be routed within an organization based upon the scheduled activity of the recipient.

VoIP Disadvantages
Reliability: VoIP is dependent on wall power and the reliability of the broadband connection. Unlike traditional telephone service, which is powered by the telephone company, if you lose power at your location, you will lose the use of the VoIP phone. Likewise if the broadband service is disrupted, telephone service will stop.
A solution to this problem is to keep a traditional telephone line active, but with minimal features. Then if a VoIP service interruption occurs, you can use the call-forwarding feature to send telephone calls to your backup location.

Security: VoIP is susceptible to the same attacks as any other IP network-based activity: viruses, worms and denial of service attacks can all effectively render VoIP inoperable. Encryption measures are being developed to counteract this threat. Network firewalls also are evolving to be able to handle large volume of VoIP traffic.

Quality: VoIP signal quality is degraded by factors that slow down packet transmission, including small network capacity, high network traffic levels, interfaces between local and wide area networks and translation between real-time protocol formats.

For computer-to-computer VoIP users, the number and activity of programs currently running on the computer can interfere with the processing necessary to support VoIP.

9-1-1 Service: When you call the enhanced 9-1-1 system, it provides an emergency dispatcher with your telephone number and the associated address even if you cannot talk to the operator. This information is then routed to the police, fire and ambulance departments in your area.

Unfortunately the network address of an IP phone, which is linked to its telephone number, has no relationship to the physical location of the device. Therefore there is no reliable way to identify the geographical location of an IP phone.

VoIP providers also have had instances where 9-1-1 calls were mistakenly routed to 9-1-1 administrative offices instead of emergency dispatchers. Some of these resulted in property loss.

As a result, the Federal Communications Commission now requires that local telephone carriers guarantee access to 9-1-1 services to VoIP providers. VoIP service providers are mandated to make their customer’s location and telephone number information available to the customer’s local 9-1-1 operator. The process for doing this requires the customer to update the location information when the telephone location changes and requires the VoIP service vendors to provide a mechanism to allow these changes to be made.

Other Considerations
• Digital television subscription services, some home satellite systems and home security systems, among others, require a standard telephone line in order to function. Currently these products have not been altered to easily use VoIP.

• VoIP providers may not offer white page listings.

VoIP holds great potential to improve communication. Telephone companies currently use VoIP to route long distance calls, and VoIP is becoming more popular among businesses as they are learning how to use it and leverage its efficiencies. Eventually VoIP or other packet-switching technology will replace circuit-switched telephone service.

VoIP disadvantages are not insignificant, however, and it may not yet be time to replace your traditional telephone service with VoIP.

You may, however, want to see how it works. If so then download some of the available VoIP software from the Internet. It only takes a few minutes to set up. Get a friend elsewhere to do the same, and you can be talking in a very short period of time.

Eric Werner, M.D., is Staff Anesthesiologist and Secretary/Treasurer, West Central Anesthesiology Group, Ltd., Central DuPage Hospital, Winfield, Illinois.