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VoIP over Cellular? 2G Networks Are a Dud

7:00 am on April 2, 2007 | Category: Cellular, Internet, VoIP, Wireless Technology

Data transmission quality is essential for the proper use of VoIP telephony services, according to new research by Patrick White, the director of wireless network security at the Stevens Institute of Technology in Hoboken, New Jersey.

White says that latency â€“ the lag between the time when one person speaks and when those sounds actually arrive at the other end â€“ can seriously disrupt and distort the flow of conversation over a Voice over IP telephone connection.

The International Telecommunications Union has declared that the lag time for a one-way VoIP signal should be no more than 150 milliseconds, or 15 one-hundredths of a second.

“That is the maximum that is really livable,” White notes, explaining that a longer delay can â€œlead to a a lot of frustration for everybody.â€

White’s research indicates that VoIP should work fine over any DSL, cable, or Wi-Fi connection, where latency usually does not exceed 30 milliseconds. Even dialup connections, where delays last around 100 milliseconds each way, should generally be adequate for IP voice applications.

Cellular data services, however, are a whole different story, with one-way time lags of between 200 and 600 milliseconds on most 1xRTT and EDGE wireless networks.

White advises cell phone users to get a 3G subscription before seriously expecting to use any wireless VoIP services. â€œDon’t waste your time with 1xRTT or Edge,” he said.

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