Global Crossing: 'Pure VoIP' all the talk

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There certainly is "More to the story"..

Noting an excerpt from the story..

"But for now, most VoIP service companies that also own their own networks have settled on time-tested telephone circuit switches"

I'm in both the call center headset telephony and speech recognition marketplaces and point to another "network-to-PSTN" problem which is ignored for the most part.

Long ago baby Bells elected to keep the frequency response of the PSTN from approx. 450Hz to approx. 3kHz, as enough significant voice data resided within this bandwidth to maintain "good enough" voice quality and it was of course much cheaper, as well. Although this frequency response was "good enough" when RBOC?s and LD carriers were transmitting /receiving pure analog across twisted pair & hardwired networks, when carriers began converting PSTN infrastructures to digital networks almost all again elected for economic (and then contemporary thinking) reasons to go with a less expensive, easier to implement sampling rate for digitizing voice to reproduce "telephone-quality" conversation - 8KHz and unfortunately this ?standard? still carries on.

Customers will suffer quality degradation from VoIP service companies carriers that hand off their network traffic to the PSTN infrastructures - even if the VoIP packet is formatted far better than the 3kHz/8 bit package the PSTN uses by default, the circuit-switched networks these calls are handed off to will tend to ignore what's presented and will re-format the signal to the familiar (and most common) 3kHz/8 bit packets, nonetheless.

Worse, if the PSTN provider uses digital to bring the call to a local CO, (where the call will again degrade via the DAC process) the traffic loses QoS as the signal is ?re-digitized? to the PSTN carrier?s outdated standards. Different VoIP & PSTN providers use varying data compression, echo cancellers, jitter control, silence suppression etc. (see another article: http://zdnet.com.com/2100-1105-5133196.html?tag=nl) and I also notice that only AT&T is honest enough to publicly acknowledge the problem to date.

In other comments (http://zdnet.com.com/5208-1105-0.html?forumID=1&threadID=1035&messageID=19567&start=-1) from a ZDNet reader.. ?The road to dominant VOIP is certainly filled with questions on timing, compatibility, vendors and more. ? One new model that is working is outsourcing the VOIP switching, management, administration and expertise to companies that host and run communications systems. ..Unified communications are better delivered by specialists who live and die voice, email and communications enhancements.? Being in the call center headset industry, we deal with large contact centers every day that experience complaints from both their CSR?s and their customers of less than satisfactory TX & Rcv call quality; this interoperability issue lies at the core of these complaints.

I have to agree with the ZDNet reader whose comments I quote above - there are significant enough quality issues to support this model, and although reliability for VoIP-to-PSTN drives the current decision philosophy, my hat?s off to VoEX.

Bill Burke,
http://www.chameleonheadsets.com
VP Call Center Sales

Posted by: wmburke   Posted on: 01/16/04 You are currently: a Guest | Members login | Terms of Use

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