While many consumer VoIP services have been phenomenally successful — many service providers are now boasting subscriber counts in the millions — I am still disappointed that virtually no VoIP operators have chosen to differentiate their services by offering wideband telephony. Most VoIP service providers are competing with traditional PSTN operators, yet very few providers do anything to differentiate their IP-based service from the 100-year-old POTS service, except perhaps to offer a lower price, and/or bundle VoIP with broadband and maybe TV service.

 

Wideband telephony is ‘hi-fidelity’ telephony. Traditional telephone calls have less than four kilohertz bandwidth (300Hz to 3400Hz) and sound worse than AM radio. Wideband telephony has almost 8 kHz (actually 50Hz to 7000Hz) of bandwidth and sounds better than FM radio, almost approaching CD quality. A good human ear can hear frequencies up to 20kHz, although most of the frequencies of the human voice are below 3kHz. That said, there is some important information contained in frequencies above 3kHz, in particular the information you need to distinguish an ‘S’ sound from an ‘F’ sound, which is why we have to say “‘S’ as in Sam, of ‘F’ as in Foxtrot,” when spelling things on the telephone. With wideband telephony the necessary high-frequency information is heard so you can actually distinguish between an ‘S’ and an ‘F’. There is also some other non verbal information in those higher frequencies, possibly even tonal indicators of the mood of the person on the other end of the line, information that would make for a much more valuable telephone experience.

 

Wideband telephony also contains more lower, or bass, frequencies, down to 50Hz, compared to the 300Hz lower limitation of the PSTN, giving voices on wideband phones much more ‘presence’.

 

For the end-user, upgrading to wideband telephony is comparable to upgrading from standard definition TV (SDTV) to high definition TV (HDTV). Once you have experienced it you will not want to go back, but until you experience it you may not think you need it. Of course you will only experience wideband telephony when calling another wideband customer, but this is a great feature for service providers. Once they get one customer using their VoIP service, that customer is going to try to convince all their friends and family to sign up for the same service so that they can all enjoy wideband communications when talking to each other.

 

Several vendors of business IP phones and IP phone systems (e.g., IP PBXs) support wideband telephony. There are many vendors out there, but I have personally used wideband phones from Avaya, Shoreline, and Polycom (News - Alert). With these systems and phones a telephone call is a wideband call as long as it remains a VoIP call. This usually means it must remain within the corporate phone network. Any calls to or from the outside world are limited by the narrowband public switched telephone network (PSTN). As a side note, Polycom also has a rather unique way of delivering wideband calls over the PSTN. Some of their non-VoIP conference room speaker phones have the ability to establish a modem (e.g., V.34) connection with a similar phone and then set up a point-to-point VoIP call over that modem connection.

 

So, if wideband telephony is available in some business phone systems, why are no VoIP operators offering wideband telephony to consumers? One reason is there aren’t any phones that can take advantage of wideband telephony over VoIP. In order to enjoy wideband telephony you need a wideband capable phone, and almost every home phone today is limited to receiving and transmitting only the frequency range required for narrowband telephony. Filters are deliberately put into phones to eliminate frequencies above 3400Hz and below 300Hz that cannot be transmitted by the PSTN. Customers could use the same IP phones that are used in wideband IP-PBXs, but they are not cheap, typically $200 and up; they are not cordless; and who really wants to replace every phone in their house?

 

Despite this, some residential gateways are shipping with the hardware capability to support wideband telephony, certainly some cable EMTAs in the U.S. and some DSL IADs in France. I am also hearing that many service provider RFPs are now requesting wideband support too. What makes a VoIP gateway ‘wideband capable’ is the inclusion of wideband capable telephone ports (also known as FXS ports, for Foreign eXchange Station). I am not sure if any of the wideband capable gateways deployed today actually have wideband support built into their VoIP software, but that could be downloaded as a future firmware update. So why would anyone ship residential gateways with wideband phone ports? Probably the intent is that once a few million wideband capable gateways are deployed then some phone manufacturer will be motivated to sell wideband phones at a consumer friendly price. Reminds me of a movie, Field of Dreams, “If you build it” (the wideband gateways), “they will come” (with wideband phones)!

 

Another reason these wideband gateways are now appearing is that they can now be built for the same hardware cost as a regular narrowband gateway. Until recently wideband FXS ports required more expensive silicon ‘SLICs’ and ‘SLACs’ (Subscriber Line Interface Circuit and Subscriber Line Access Circuit), but today wideband FXS solutions from some vendors no longer carry a price premium. There was also a limitation with the main broadband network processor at the heart of these residential gateways. A wideband phone call generates a lot more data than a narrowband call. Narrowband calls use 8-bit samples collected at 8 kHz rates, resulting in a 64 kbps data stream, but wideband calls use 16 bit samples collected at 16 kHz rates, yielding a 256 kbps data stream. 256 kbps can be a significant percentage of a user’s available broadband bandwidth. Some unfortunate customers may have ‘broadband’ service with as little as 1 Mbps downstream and 128 kbps upstream, clearly not enough bandwidth to support an uncompressed wideband call. So, while many VoIP service providers don’t bother to compress narrowband calls today, they will need to compress these bandwidth hogging wideband calls. The algorithms that are used to compress wideband voice (such as G.722) can be pretty complex and require quite a bit of CPU performance, something that wasn’t available inexpensively until recently.

 

There are also a few residential gateways shipping today with built in cordless phone base stations, which typically have support for special wideband capable cordless phones. The latest worldwide digital enhanced cordless telecommunications (DECT (News - Alert)) standard, known as Cordless Advanced Technology – internet and quality (CAT-iq), specifies wideband telephony and so all silicon vendors offering CAT-iq chipsets will have to include wideband support or they will not be able to claim they meet the standard. If the wideband capable chipsets are available, it is quite likely that phone manufacturers will build wideband phones.

 

Some observers speculate that wideband telephony may even precipitate the end for regular FXS phone ports in VoIP gateways, as vendors scramble to embed DECT base stations into their gateways to support service providers deploying wideband VoIP.

 

I not sure this will happen, at least not for a very long time. End customers need FXS ports to support their existing narrowband phones, not to mention home alarm systems and maybe even fax machines. Also, many service providers deploy their gateways on the side of the house and hook into the home phone network just like a traditional Network Interface Device (NID) would (in fact these gateways are sometimes called iNIDs). This type of ‘NID-like’ gateway needs FXS ports to connect to the home phone network. This type of gateway is most often seen in North American deployments. Many cable companies deploy this way, as does Verizon with their FiOS fiber to the home service (FTTH), and also AT&T (News - Alert) with their fiber to the curb (FTTC) service with DSL connections from the curb to the home.

 

So, wideband telephony, an exciting feature that has been ‘coming soon’ for a long time, but may now actually be on its way, offering clear benefits to end users that should result in more and more people switching to VoIP services.

 

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