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What is HD voice?

Yesterday, Sprint 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 only a modified version of the HTC I XL that is heading to AT&T — there is a particular feature that stands out: HD voice. For the first time in several years, voice calling is getting an upgrade. Just what is HD voice and what does it offer?

Hard disk voice is an umbrella term which refers to technologies that enhance the quality of an audio phone call, or the audio portion of a video call. Depending on the calling organization being used, HD voice may or may not be available.

Most people commonly feel HD vocalism when using VoIP platforms like Skype on their computers. Even so, most people exercise non consider Skype an Hd voice platform because it is not a telephone system. With the transition to predominantly digital cellular/satellite communications, every bit opposed to the traditional terrestrial circuit-switched telephone network, HD vocalisation became possible for telephony. Even better, governments effectually the world are at present considering replacing traditional circuit-switched telephone networks (POTS) with optical fiber packet-switched VoIP networks.

HTC Evo 4G LTEFor cellular (and possibly hybrid cellular/satellite) networks, HD voice has been in evolution since 2000. In the terminal 2 years, the specifications for HD vox on CDMA2000, GSM, HSPA+, and LTE take been finalized. However, this year is the yr that device makers are finally beingness offered modem chipsets (from the likes of Qualcomm) that take full back up for Hard disk drive voice.

Hard disk drive vocalisation on CDMA2000 requires upgrading the 1X carrier to 1X Avant-garde. This new network infrastructure upgrade boosts capacity and range of a given jail cell by upwards to seventy%, but more importantly it widens the 1X channel to nearly 300Kbps, giving more than enough room to support a brand new, higher quality audio codec. The EVRC-NW (Enhanced Variable Rate Codec – Narrowband/Wideband) codec for CDMA2000 systems is a redesigned codec that can calibration from the narrowband channel sizes currently supported in CDMA2000 to new wideband channel sizes provided in CDMA2000 1X Advanced. Additionally, a multi-microphone noise canceling system is required to accept full advantage of the codec. The new codec allows for properly encoding audio in the 50Hz-4KHz range at a 16KHz sampling rate, as opposed to half that for the older narrowband-only codec. Additionally, the wideband codec actually goes upward to 7KHz instead of 4KHz, offer slightly amend audio recording capabilities.

On the GSM side of things (which includes 2G GSM, HSPA+, and LTE), HD voice is largely a core network upgrade. The audio channel for the base stations needs to be widened a chip 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 HD vocalisation upgrade is easier on the GSM side, since no massive equipment upgrades are required at the base station/belfry side.

There are restrictions for currently available HD voice implementations, though. It looks similar the CDMA2000 and the GSM family variants of HD voice are not interoperable for the foreseeable future, so GSM calls to CDMA phones and vice versa will drop down to narrowband codecs that the 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 Avant-garde and the new codec (otherwise it falls back to 1X and the older codec). For GSM networks, all handsets participating in the call must support the AMR-WB codec.

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

For wireline networks (standard telephony), HD vocalisation is not still available. All currently available wireline telephony services (including VoIP based ones like Vonage) use narrowband spoken communication codecs, so there'southward no capability for HD voice. While SIP does back up information technology (and is the footing for VoLTE Hard disk drive phonation back up), most wireline networks cap the bandwidth to 12Kbps to forestall too much information from going through. Consequently, higher-quality speech communication codecs cannot be used.

T-Mobile 4G coverage mapCurrently, there are no networks in the The states that offer Hd vocalisation. T-Mobile United states of america'south network is technically capable of information technology, since the new WiFi Calling characteristic uses the same applied science as VoLTE. However, it is non currently enabled; it will be enabled when T-Mobile deploys LTE. Dart has declared that information technology will enable it with the upgrade to CDMA2000 1X Advanced, merely information technology will likely exist mostly useless until tardily 2013. It volition also support HD phonation through VoLTE next year. No other CDMA carriers will offer HD vocalisation through CDMA2000 1X Advanced. Verizon Wireless and AT&T will have support for the technology with VoLTE deployment, only only Verizon Wireless has announced plans to offer support for Hard disk drive voice on LTE.

Sprint can trumpet the feature all it wants, only Hard disk voice will remain a useless feature that hardly anyone will get to experience until late 2013 at the earliest. And even then, most all subscribers will feel Hard disk drive voice through LTE, non CDMA2000 1X Advanced. If you want to experience HD voice, endeavour using a computer-based VoIP solution for now.