November 18, 2010

By David Sims

TMCnet Contributing Editor

 

We suppose it would be fair to say VoIP has been a net plus for the telecommunications industry. As industry observer James Waldrop notes, “Consumers have used services such as Vonage (News - Alert) and Skype to lower telephone bills and connect with loved ones around the world. Businesses have reaped far greater benefits from VoIP when they have installed IP-enabled telephone systems and hosted PBX (News - Alert) services.”

Many have, in fact, “redesigned their operations around the use of VoIP reducing personnel,” as Waldrop says, extending it to reducing office space and overhead while improving customer service.

Not every VoIP implementation is a success story, though. We know, sorry to be the ones to break the news. VoIP does come with some problems such as dropped calls and garbled speech, voice quality problems that “can be the result of many factors including insufficient Internet speed, poor ISP service, wiring, viruses, improper voice packet prioritization and many more,” Waldrop says.

Now, in Waldrop’s estimation, here’s what not to do: “Do not start changing settings and equipment without a plan. VoIP issues can be caused by dozens of factors including the Internet Service Provider (ISP). Potential trouble areas must be systematically eliminated. Do not give up on VoIP and its many benefits. Your problem can be fixed.”

Telephony boards “must continuously transfer voice buffers to the host CPU, so having the ability to configure the frequency at which this is done will help optimize the performance of the CPU,” accordingto Frederic Dickey on TMCnet.com recently. “Some boards are hardwired to interrupt the CPU at every millisecond for every call to perform this task, while others are configurable for longer periods so that the CPU can be relieved to address other tasks. As with RTP packet sizes, there is a fine balance to keep between CPU occupancy and delays introduced.”

On-board echo cancellation and on-board tone detection are other functions that take processing power away from the CPU and must be configured correctly. In addition, on-board HDLC framing, which is required to pass call control protocol data such as ISDN D-channels from the network to the host, consumes CPU cycles.

There are many other considerations, such as network design, on which we have not touched. But clearly, deploying an open source VoIP systems introduces a lot of changes and requires careful consideration of many network settings and functions, as well as the right selection of hardware and computing platforms.

When deployed correctly following these guidelines, VoIP systems based on open source can provide high-quality and efficient voice communication for enterprises.

David Sims is a contributing editor for TMCnet. To read more of David’s articles, please visit his columnist page. He also blogs for TMCnet here.

Edited by Tammy Wolf