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What is HD voice?

Yesterday, Dart and HTC announced the HTC Evo 4G LTE, the latest in the series of Evo phones from Sprint. While the device is largely unexceptional — it is simply a modified version of the HTC I 40 that is heading to AT&T — there is a detail feature that stands out: Hd vocalism. For the beginning time in several years, phonation calling is getting an upgrade. But what is HD voice and what does it offer?

HD vocalism is an umbrella term which refers to technologies that raise the quality of an audio call, or the audio portion of a video call. Depending on the calling organization beingness used, Hard disk drive vocalization may or may not be available.

Nigh people normally experience HD voice when using VoIP platforms like Skype on their computers. However, most people exercise not consider Skype an Hd vocalisation platform because information technology is not a telephone organisation. With the transition to predominantly digital cellular/satellite communications, every bit opposed to the traditional terrestrial circuit-switched telephone network, HD voice became possible for telephony. Even ameliorate, governments around the world are at present considering replacing traditional circuit-switched phone networks (POTS) with optical cobweb package-switched VoIP networks.

HTC Evo 4G LTEFor cellular (and possibly hybrid cellular/satellite) networks, Hard disk drive voice has been in development since 2000. In the last 2 years, the specifications for Hard disk vocalisation on CDMA2000, GSM, HSPA+, and LTE have been finalized. Nevertheless, this twelvemonth is the year that device makers are finally being offered modem chipsets (from the likes of Qualcomm) that have total support for Hard disk drive voice.

HD phonation on CDMA2000 requires upgrading the 1X carrier to 1X Avant-garde. This new network infrastructure upgrade boosts capacity and range of a given prison cell by up to 70%, but more than importantly it widens the 1X channel to about 300Kbps, giving more than enough room to support a brand new, higher quality sound codec. The EVRC-NW (Enhanced Variable Charge per unit Codec – Narrowband/Wideband) codec for CDMA2000 systems is a redesigned codec that tin scale from the narrowband aqueduct sizes currently supported in CDMA2000 to new wideband channel sizes provided in CDMA2000 1X Avant-garde. Additionally, a multi-microphone noise canceling system is required to take full reward of the codec. The new codec allows for properly encoding audio in the 50Hz-4KHz range at a 16KHz sampling rate, every bit opposed to half that for the older narrowband-just codec. Additionally, the wideband codec actually goes up to 7KHz instead of 4KHz, offering slightly better audio recording capabilities.

On the GSM side of things (which includes 2G GSM, HSPA+, and LTE), HD vox is largely a core network upgrade. The audio channel for the base of operations stations needs to be widened a scrap to make room for the AMR-WB (Adaptive Multi-Rate Wideband) codec, though. AMR-WB and EVRC-NW offering largely the same benefits and have the same requirements. However, the Hard disk drive vocalization upgrade is easier on the GSM side, since no massive equipment upgrades are required at the base of operations station/tower side.

In that location are restrictions for currently available HD voice implementations, though. It looks like the CDMA2000 and the GSM family variants of HD voice are not interoperable for the foreseeable futurity, so GSM calls to CDMA phones and vice versa volition drop downwards to narrowband codecs that the electric current interoperability systems support. For CDMA2000 networks, every participant in a telephone call must be connected to a cell site that supports CDMA2000 1X Avant-garde and each handset connected to the 1X Advanced cells must have a chipset supporting 1X Advanced and the new codec (otherwise it falls dorsum to 1X and the older codec). For GSM networks, all handsets participating in the call must support the AMR-WB codec.

In LTE, Hard disk drive voice is really built into the VoLTE standard, because VoLTE uses AMR-WB. As long every bit the device supports AMR-WB, then Hard disk drive vocalism is possible. The just thing left would be for the network operator to enable HD voice on the network.

For wireline networks (standard telephony), HD vocalization is not yet available. All currently available wireline telephony services (including VoIP based ones like Vonage) use narrowband oral communication codecs, so in that location'southward no capability for HD voice. While SIP does support it (and is the basis for VoLTE HD vocalism support), nearly wireline networks cap the bandwidth to 12Kbps to prevent too much data from going through. Consequently, college-quality speech codecs cannot be used.

T-Mobile 4G coverage mapCurrently, in that location are no networks in the United States that offer Hard disk voice. T-Mobile Us'due south network is technically capable of information technology, since the new WiFi Calling characteristic uses the same technology as VoLTE. Yet, it is not currently enabled; it will be enabled when T-Mobile deploys LTE. Sprint has declared that it volition enable information technology with the upgrade to CDMA2000 1X Avant-garde, but it will likely be mostly useless until late 2013. Information technology volition also support HD vocalisation through VoLTE next twelvemonth. No other CDMA carriers will offer Hard disk drive voice through CDMA2000 1X Advanced. Verizon Wireless and AT&T will take support for the technology with VoLTE deployment, but but Verizon Wireless has appear plans to offer support for Hard disk voice on LTE.

Sprint can trumpet the feature all information technology wants, but Hard disk vox will remain a useless feature that hardly anyone will go to feel until late 2013 at the earliest. And even and so, about all subscribers will feel HD voice through LTE, non CDMA2000 1X Advanced. If you want to feel HD phonation, attempt using a calculator-based VoIP solution for now.