Creating a secure and reliable VoIP solution

If you're considering a switch to VoIP, you may be wondering about security and reliability issues.

You know VoIP uses the internet (in most cases) to transmit calls, and internet security breaches are featured in the news almost daily. Perhaps the biggest challenge to building a secure VoIP infrastructure, however, is the trade-off you must often make between security and performance. This trade-off exists on data networks, too, but it presents more of an issue on voice networks because quality of service is so dependent on performance.

Let's take a look at the problem and some things you can do to work around it.

How to make VoIP more reliable
The phone company has a reputation for reliability: customers are used to getting a dialling tone every time they pick up the phone; they're used to calls going through to the correct party; and they're used to clear communications on that call until one of the parties terminates it. They aren't willing to settle for less.

The trouble with VoIP
Many businesses tried VoIP when it first became available; they didn't cancel their PSTN service and embrace IP telephony because they didn't find VoIP to be entirely trustworthy. The service worked great — sometimes. Other times, users would pick up the phone to find there was no dialling tone, and would have to reboot the VoIP box before making or receiving a call. Sometimes calls went through with no problem, but calls to certain phone numbers, especially those on corporate PBX systems, resulted in so much echo that users had to switch to the landline when talking to those people. Other weird problems would occasionally pop up, such as caller ID reporting a totally different number than the one from which the call was made. The overall consensus was: VoIP had 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 and intermittent loss of service — are the same ones that plagued mobile-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 rarer.

Indeed, many VoIP users who have stayed with the technology have noticed fewer problems this year than just a couple of years ago. Sometimes quality improves dramatically when you switch out the provided ATA (VoIP box) for a newer model; or, in some cases, you can simply upgrade its software. If you've been living with a less-than-perfect VoIP service, ask your provider about upgrading the equipment.

The nature of VoIP
Although advances make VoIP likely to improve, the nature of VoIP does introduce some factors that make it less reliable than PSTN. You'll recall that PSTN lines use circuit-switching technology; this means that, for the duration of any particular call, there is a dedicated circuit that stays open between the caller and receiver for the entire time. That circuit can't be used by anyone else during that time.

VoIP calls travel over a packet-switched network (the internet). There is no constant connection maintained. Instead, the voice signal is digitised and broken into small portions (packets) that are sent through a series of routers until they reach the recipient. Different packets may take different routes; they're reassembled at the destination and turned back into voice. Multiple transmissions (of voice or data) can share the same lines. Because packets can be routed along whatever line is least congested at the time, it's more efficient and cost-effective. But there is also the potential for packets to get lost or misrouted. Problems with internet routers along the way can affect the quality of your call, or even 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, the phone lines themselves don't need to be powered at your site 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, the 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…