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What is HD voice?

Yesterday, Sprint and HTC announced the HTC Evo 4G LTE, the up-to-the-minute in the series of Evo phones from Sprint. While the device is largely run-of-the-mine — it is bu a modified version of the HTC One XL that is heading to AT&T — thither is a particular feature that stands out: HD representative. For the first time in several eld, voice calling is acquiring an acclivity. But what is HD voice and what does it offer?

HD voice is an comprehensive term which refers to technologies that raise the quality of an audio prognosticate, or the audio frequency portion of a video call. Depending on the calling system being used, HD sound may OR English hawthorn not be available.

Nearly multitude commonly experience HD voice when using VoIP platforms alike Skype on their computers. However, most people do not consider Skype an HD voice weapons platform because it is non a phone system. With the passage to predominantly integer cellular/satellite communication theory, as anti to the traditional terrestrial circuit-switched telephone network, HD vocalise became possible for telephony. Even up better, governments around the world are now considering replacing traditional circuit-switched telephone set 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 development since 2000. In the last cardinal years, the specifications for HD voice on CDMA2000, GSM, HSPA+, and LTE have been finalized. However, this twelvemonth is the year that twist makers are at long last existence offered modem chipsets (from the likes of Qualcomm) that have full support for HD voice.

HD vocalism on CDMA2000 requires upgrading the 1X letter carrier to 1X Advanced. This new network substructure upgrade boosts capacitance and range of a given cell by sprouted to 70%, but more importantly it widens the 1X channel to about 300Kbps, bounteous more than enough room to back a firebrand new, higher select audio codec. The EVRC-Northwest (Enhanced Variable Rate Codec – Narrowband/Wideband) codec for CDMA2000 systems is a redesigned codec that throne scale from the narrowband channelise sizes presently supported in CDMA2000 to new wideband channel sizes provided in CDMA2000 1X Ripe. Additionally, a multi-microphone racket canceling arrangement is required to take full vantage of the codec. The sunrise codec allows for the right way encoding audio in the 50Hz-4KHz range at a 16KHz sampling plac, as opposed to half that for the older narrowband-only when codec. Additionally, the wideband codec actually goes up to 7KHz instead of 4KHz, offering slightly better sound recording capabilities.

On the GSM side of things (which includes 2G GSM, HSPA+, and LTE), HD voice is largely a core mesh upgrade. The sound channel for the base stations inevitably to embody widened a bit to make room for the AMR-Wb (Adaptive Multi-Rate Band) codec, though. AMR-WB and EVRC-Northwest offer mostly the aforesaid benefits and wealthy person the same requirements. Still, the HD voice upgrade is easier on the GSM side, since no massive equipment upgrades are needed at the alkali place/tower side.

There are restrictions for currently available HD voice implementations, though. It looks like the CDMA2000 and the GSM kin variants of HD voice are not interoperable for the foreseeable future, so GSM calls to CDMA phones and frailty versa will swing down to narrowband codecs that the afoot interoperability systems support. For CDMA2000 networks, every participant in a call essential be connected to a cell internet site that supports CDMA2000 1X Advanced and each handset connected to the 1X Advanced cells must let a chipset supporting 1X Advanced and the new codec (other it falls second to 1X and the older codec). For GSM networks, all handsets participating in the call must support the AMR-WB codec.

In LTE, HD voice is actually built into the VoLTE standard, because VoLTE uses AMR-WB. As semipermanent as the device supports AMR-WB, and so HD voice is possible. The only thing left would be for the network operator to enable HD voice happening the network.

For wireline networks (normal telephone), HD voice is non yet available. All currently available wireline telephony services (including VoIP based ones like Vonage) use narrowband speech codecs, so at that place's No capability for HD voice. While SIP does support it (and is the basis for VoLTE HD spokesperson support), most wireline networks cap the bandwidth to 12Kbps to prevent too a lot data from going through and through. Consequently, higher-quality speech codecs cannot be put-upon.

T-Mobile 4G coverage mapCurrently, at that place are no networks in the United States that offer HD vocalism. T-Versatile USA's network is technically confident of it, since the unprecedented WiFi Calling feature uses the duplicate technology as VoLTE. However, it is not currently enabled; it will be enabled when T-Mobile deploys LTE. Sprint has declared that it will enable IT with the upgrade to CDMA2000 1X Sophisticated, but it will in all probability exist mostly useless until late 2013. It will also support HD voice through VoLTE next year. No other CDMA carriers will offer HD voice through CDMA2000 1X Advanced. Verizon Wireless and AT&T volition have support for the technology with VoLTE deployment, but only Verizon Wireless has announced plans to offer support for HD voice on LTE.

Sprint fundament cornet the feature every last it wants, only HD voice will remain a ineffective feature that hardly anyone will bother know until late 2013 at the early. And even then, nearly altogether subscribers will experience HD voice through with LTE, not CDMA2000 1X Advanced. If you neediness to experience HD voice, try using a data processor-based VoIP answer for now.