Networking

Making VoIP more reliable

With all the talk about the convenience and affordability of VoIP, how come people are reluctant to cut the landline cord? Deb Shinder poses this question to business managers and finds that a standard line runs through their answers.

Almost everyone has heard by now that Voice over IP (VoIP) technology can save you money on phone calls, whether you're a consumer, small business owner, or running an enterprise-level corporation. In fact, using VoIP can reduce your telephone costs by hundreds or even thousands of dollars per month if you make a lot of long distance calls. Why, then, do landlines still exist at all? Why isn't everyone using VoIP?

I talked to a group of managers of small- and medium-sized businesses, and the biggest concern they expressed to us—indeed, their most common reason for not switching to VoIP—can be summed up in one word: reliability.

The phone company has a reputation for reliability. Customers are used to getting a dial tone every time they pick up the phone. They're used to their calls going through to the correct party. And they're used to having clear communications up until the moment one of the parties terminates the call. They aren't willing to settle for less.

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The trouble with VoIP

Many of these business people tried VoIP when it first became available. And the reason they didn't cancel their Public Switched Telephone Network (PSTN) service and embrace IP telephony was because they didn't find VoIP to be entirely trustworthy. One user reported that the service worked great—sometimes. Other times he'd pick up the phone to find there was no dial tone, and would have to reboot the VoIP box before he could make or receive a call. Another said most calls went through with no problem, but calls to certain phone numbers, especially those on corporate PBX systems, resulted in so much echo that she had to switch to the landline when talking to those people. A few reported downright weird problems, such as caller ID reporting a totally different number than from the actual originating phone. The overall consensus: VoIP has great potential but, like beta software with cool features, it's just a little too flaky for everyday use.

In fact, the complaints about VoIP quality—poor sound, dropped calls, intermittent loss of service—are the same ones that plagued cell phone technology in its early days and, indeed, the same ones that occurred with PSTN when the whole phone system was in its infancy. That should give us hope that, as VoIP matures, these problems will become more and more rare.

The nature of VoIP

The nature of VoIP, however, introduces some factors that make VoIP inherently less reliable than PSTN. PSTN lines use circuit switching; this means that during the duration of any particular call, there is a dedicated circuit that stays open between the caller and receiver for the entire time. No one else can use that circuit during that time.

VoIP calls travel over a packet-switched network—the Internet. There is no constant connection maintained. Instead, the voice signal is digitized and broken into small portions (packets) sent through a series of routers until they reach the recipient. Different packets may take different routes before they reassemble back into voice at the destination. Multiple transmissions (of voice or data) can share the same lines. Because the signal can route packets along whatever line is least congested at the time, it's more efficient and cost effective. But packets may get lost or misrouted, and problems with Internet routers along the way can affect the quality of your call, or whether it goes through at all.

VoIP dependencies

Another reason PSTN is more reliable is its relative independence from an on-site power source. In a business or even in a home that uses cordless phones, your equipment (PBX, phone base station, etc.) may require electricity. However, it's not necessary to power the phone lines themselves at your site in order for them to work. They draw their power from the central office, so if you have an electrical outage at your office or home, you can still make phone calls.

Your VoIP line is dependent on an appliance that requires power to work. If you lose power, the line goes down. It's also dependent on your Internet connection; if that goes down, those packets that contain your call data have no way to reach their destinations. Even the normal momentary "glitches" to which broadband Internet services are prone can cause transmission errors that may interrupt your phone calls. And, of course, viruses, worms, and hack attacks that bring down the network can also bring down your phone system when it's IP-based.

Increasing VoIP reliability

You can address many of these problems by using an enterprise-level VoIP provider. But what if you have a small business and can't afford to go that route? Fortunately, there are steps you can take to make your VoIP deployment more reliable, even when using affordable, consumer-oriented providers. These include:

  • Power backup (UPS and/or generator). This will continue supplying electrical power to your VoIP equipment and Internet router if there's a power failure.
  • Redundant Internet connections. You can use some routers to aggregate two broadband or T-carrier connections from different providers to provide more bandwidth and to automatically failover when one connection goes down.
  • Dedicated Internet connection for VoIP. Keeping your VoIP line on its own Internet connection separate from your data network allows you to isolate it from any viruses or attacks that threaten your data network, and to protect it with its own firewall. You can configure the firewall to block everything but the specific protocols needed for the VoIP communications.
  • Redundant VoIP lines. If you need multiple voice phone lines, you don't have to get them all from the same VoIP provider. Although it may be more convenient and you may get a better price, having different lines from different providers can keep you talking if there are problems at the provider's end that cause your voice services to be unavailable.
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    About

    Debra Littlejohn Shinder, MCSE, MVP is a technology consultant, trainer, and writer who has authored a number of books on computer operating systems, networking, and security. Deb is a tech editor, developmental editor, and contributor to over 20 add...

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