Reality Check: How Hard Are IP Phones, Really?

Case Study: With Internet Protocol telephone systems, network managers need new tools to make sure calls go through-and don't sound like gibberish.

Fidelity Investments, the Boston-based financial services firm, uses voice-over-IP technology in most of its international offices to save on long-distance charges to other Fidelity locations. To date, its put IP-based phones on the desks of about 10% of its 30,000 employees.

Mike Brady, Fidelitys senior vice president of telecommunications, leads a team that runs the voice networks and ensures calls meets the companys quality standards. Its a tough job, not least of which is because hes usually thousands of miles away from the people who need his help.

But the trickiest part, Brady says, stems from the fact that data networks were not intended to carry voice. Theyre resilient for data: IP networks automatically reroute transmissions if one network segment fails. The trouble is, that trait can absolutely murder phone calls, because increasing the time it takes for the data that comprises a voice call to reach its destination—by even a quarter of a second—can turn a conversation into gibberish.

Traditional data network management tools cant always provide enough information to see glitches that affect voice. Using regular network monitoring systems, "we can understand delays between any two points in a network," Brady says. "But with voice-over-IP, thats no longer good enough."

Fidelity uses a technology called quality of service, which instructs a network to always send voice traffic ahead of other data, to minimize the chance of delays. But today such quality-of-service information doesnt carry over from one network to another (although newer technologies, such as Multiprotocol Label Switching, or MPLS, promise to do this once theyre widely deployed).

Brady had to find a better way to crack this nut. So, for the past year, Fidelity has used monitoring equipment from Brix Networks, a small Boston-area firm, to catch degradation of IP phone service before complaints start trickling in. Brix boxes place simulated voice calls every few minutes from various points on the network, and can detect when sound quality is going south. "Brix helps us find and fix the gray failures," Brady says.

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