How to ensure the quality of internet VoIP

1. Make sure you have the bandwidth you need. One of your first self-help steps should be to make sure that you have the right amount of bandwidth. As the most successful small-business VoIP provider, with some 8,000 customers, Packet8 service provider 8x8 Inc. provides a reasonable basis for comparison. Its bandwidth rule of thumb is that 25 to 30 percent of the workers at a typical company are on the phone at any one time. Give yourself a cushion and assume it'll be 40 percent. 8x8 uses D.729 compression technology to squeeze a voice call into 25 Kbps of bandwidth. That means for a 10-employee business, you'll need 100 Kbps to carry calls alone, on top of all your other data needs. If your provider uses different technology, find out what it is and adjust your estimates accordingly.

2. Make sure you have the right kind of bandwidth. The "A" in "ADSL" stands for "asymmetric." That means that the speeds are different in different directions. That may be OK for home users who download more files than they upload. But if you do more back-and-forth business than Web surfing on your office network, it might sometimes be harder for people to hear you than for you to hear them. 8x8 Inc. recommends at least SDSL (symmetric DSL) and perhaps fractional T1 connections.

3. Make sure you're not trying to do too much on your LAN. Companies that send a lot of big files around the office network, like graphic images that hog hundreds of megabytes, won't leave much room for voice traffic. Make sure you have a comfortable bandwidth margin even during periods of peak usage. Either that, or prohibit employees from sending large email attachments whenever the boss is on the phone. You also might consider getting a router that prioritizes voice over data. 8x8 sales and marketing VP Huw Rees said that will set businesses back $200 to $300, rather than the $50 or so for a simpler model. He added, though, that with sufficient bandwidth, and enhanced router may not be necessary.

4. Even with normal traffic levels, make sure your gear is up to the job. Some small businesses, believe it or not, try to make do with residential networking gear. A router that lets your family share the DSL connection at home won't work at the office. You might not mind it when a YouTube video stream interrupts your daughter's GTalk call to her Facebook pal across the country, but your sales superstar whose big closing pitch gets cut off because everyone is logged on to your competitor's Webinar will surely mind it a lot.

5. Intimidate your provider with tough technical questions. Ask your VoIP provider how much packet loss its technology can handle without calls sounding like two robots talking. If it tells you anything more than 1 percent, ask for a discount or go elsewhere. When the provider's gear buffers packets to cope with jitter, how much delay does that introduce? There may be no right answer to that question, but there is also the question of the maximum total delay its service typically experiences. More than 250 to 300 milliseconds, and the callers start talking over each other, one of the most irritating aspects of poor call quality.

6. Speaking of delay, ask your provider about its provider. Does it use a name-brand carrier with a network far-flung enough to deliver the voice packets on one hand to a POP (Point of Presence) near you, and on the other hand to gateways near the people you're calling, wherever they are? If it does, latency problems should be minimal, because the only uncontrolled part of your packets' journey will be the last mile over the open public Internet from the POP to you. 8x8 says that latency on Level 3's backbone, which it uses exclusively, has become insignificant.

7. Speaking of quality, ask your provider how it tests it. Does it even test for voice quality using MOS (Mean Opinion Score), a standard measure for how people perceive the quality of voice calls? (A score of 4.0 is "toll quality.") If so, does the provider mathematically derive MOS values solely from IP network performance stats? If it does, it might be doing a superb job of delivering voice packets that contain grotesquely distorted sounds. Psytechnics CTO Mike Hollier insists that it's necessary to record actual calls themselves and analyze them to provide meaningful MOS readings. 8x8, for its part, said that it used to do that, but the company eventually found that it understood the correlation between the mathematically derived scores and the quality users perceived well enough that it could cut back on such end-to-end testing.

8. Ask your provider about troubleshooting. If your call quality isn't up to par, is the provider's solution a page of frequently asked questions and an email address for contacting technicians? 8x8's Rees said that with the days of erratic Internet performance long (at least a year) in the past, most current problems result from bad LAN setups, including culprits such as faulty wiring and misconfigured routers. That's the kind of problem that a set of generic answers can't begin to address. 8x8 puts customers in touch with wiring specialist CSI Inc. when they need more individualized help.

From all this, it's clear that all Internet VoIP is not created equal. And even though you may be shelling out only $50 per month on your credit card for unlimited nationwide calling, it doesn't mean that all you can do is pay your money and take your chances.