Voice over LTE

VoLTE is an acronym for Voice over LTE, which is based on the IP Multimedia Subsystem (IMS) network, with specific profiles for control and media planes of voice service on LTE defined by GSMA in PRD IR.92.^[1] This approach results in the voice service (control and media planes) being delivered as data flows within the LTE data bearer. This means that there is no dependency on (or ultimately, requirement for) the legacy circuit-switched voice network to be maintained. VoLTE has up to three times more voice and data capacity than 3G UMTS and up to six times more than 2G GSM. Furthermore, it frees up bandwidth because VoLTE’s packets headers are smaller than those of unoptimized VoIP/LTE.^[2]

History

In May 2014, Singtel introduced the world's first commercial "full-featured" VoLTE service in Singapore, initially only in combination with the Galaxy Note 3, it was subsequently expanded to the Samsung Galaxy S6 series, iPhone 6s, LG G4 and Sony Xperia Z3+ .^[3]

In June 2014, KT showcased the world’s first cross-border roaming services based on Voice over LTE. The South Korean operator partnered with China Mobile to develop VoLTE roaming services.^[4]

In October 2014, China Mobile, KPN and iBasis successfully implemented the first international VoLTE roaming between mobile operators based on IMS local breakout architecture with home routing systems.^[5]

In November 2014, Verizon and AT&T have announced the companies are enabling VoLTE-to-VoLTE connections between their respective customers. VoLTE interoperability between Verizon and AT&T customers was expected to be available in 2015. Testing and design are being done between both companies using third party networks such as Alcatel-Lucent.^[6]

On 11 July 2015, SEATEL Cambodia have announced the world's first commercial 100% VoLTE service without 2G/3G in Cambodia.^{[7][8][9][10][11]}

On 16 September 2015, Telstra announced that it had started enabling VoLTE across its network, including calling to National Broadband Network and business and enterprise services with HD handsets.^[12]

Deployment

A list of commercial VoLTE deployments around the world can be found in the main article above.

For planned VoLTE deployments see GSA Evolution to LTE report - VoLTE global status (Page 87ff).

Devices

Mobile devices with support for VoLTE
Brand	Name	Note
Apple	iPhone 6 (Plus)	[13]
	iPhone 6S (Plus)	[14]
	iPhone SE	[15]
Andromax	R2	[16]
	E2	[17]
BlackBerry	Priv	[18]
Fujitsu	Arrows NX	[19] F-02G, F-05F, F-04G
HTC	Desire 524	[20]
	Desire 526	[20]
	Desire EYE	[21]
	J butterfly	[22] HTV31
	One (M8)	[23]
	One M9	[24]
Huawei	Ascend D2 LTE	[25]
	Ascend P7	[26]
iida	INFOBAR A03	[27]
Kyocera	BASIO	[28]
	TORQUE G02	[29]
	URBANO V01	[30]
	URBANO V02	[31]
LG	Disney Mobile on docomo	[19] DM-01G
	G Flex G Flex 2	[32]
	G Pro	[25] F240S
	G2	[33]
	G3	[34]
	G4	[20]
	isai vivid	[35] LGV32
	isai VL	[36] LGV31
	Lancet	[20]
	Optimus GX	[25] F310L
	Optimus LTE 2	[25] F160LV
	Optimus LTE III	[25] F260S
	Optimus Vu II	[25] F200L
	LG Stylo/LG Stylus	[37] LG Stylo/Stylus
	Spirit LTE	Indian Version
Vu 3	[25] F300
LYF	LYF Earth 1	[38]
	LYF Water 1	[39]
	LYF Water 2	[40]
	LYF Wind 6	[41]
	LYF Flame 1	[42]
Microsoft	Lumia 950	[43]
	Lumia 950XL	[43]
	Lumia 640	[43]
	Lumia 640 XL	[43]
	Lumia 550	[43]
	Lumia 735	[20]
Motorola	Droid Maxx	[20]
	Droid Mini	[20]
	Droid Turbo	[44] XT-1254
	Nexus 6	[20]
	Moto G (3rd Gen)	XT1550
Nokia	Lumia 830	[45]
Pantech	Vega Iron	[25] IM-A870S
	Vega N°6	[25] IM-A860S
	Vega R3	[25] IM-A850L
	Vega Secret Note	[25] IM-A890S
Samsung	Galaxy Avant	[46]
	Galaxy Core Prime	[20]
	Galaxy Golden	[25] SHV-E400
	Galaxy Grand	[25] SHV-E270
	Galaxy Light	[32]
	Galaxy Note II LTE	[25] SHV-E250S
	Galaxy Note 3	[3][47]
	Galaxy Note 4	[48]
	Galaxy Note 5	[49]
	Galaxy Note 10.1 LTE	[25]
	Galaxy Note Edge	[19] SC-01G
	Galaxy Pop	[25] SHV-E220S
	Galaxy Round	[25] SM-G910S
	Galaxy S III LTE	[25] SHV-E210
	Galaxy S4	[25] SCH-R970C
	Galaxy S4 mini LTE	[50] GT-i9195
	Galaxy S4 Zoom	[25] SM-C105S
	Galaxy S5	[32]
	Galaxy S5 Active	[19] SC-02G
	Galaxy S6 (Edge)	[51]
	Galaxy S6 Edge+	[52]
	Galaxy S7 (Edge)
Galaxy Win	[25] SHV-E500S
Sharp	AQUOS CRYSTAL	[53]
	AQUOS CRYSTAL 2	[53]
	AQUOS CRYSTAL X	[53]
	AQUOS EVER	[19] SH-04G
	AQUOS PAD	[19] SH-06F, SH-05G
	AQUOS SERIE	[54] SHV32
	AQUOS SERIE mini	[55] SHV31
	AQUOS Xx	[53]
	AQUOS ZETA	[19] SH-01G, SH-04F, SH-03G
	Disney Mobile on docomo	[19] SH-02G
Sony	Xperia A4	[19] SO-04G
	Xperia SP M35t	[25]
	Xperia Z2	[19] SO-03F
	Xperia Z2 Tablet	[19] SO-05F
	Xperia M4 Aqua Dual	[19] SO-06F
	Xperia Z3	[19] SO-01G, D6653
	Xperia Z3 Compact	[19] SO-02G
	Xperia Z4	[56] SO-03G
	Xperia Z4 Tablet	[19] SO-05G

Voice quality

To ensure compatibility, 3GPP demands at least AMR-NB codec (narrow band), but the recommended speech codec for VoLTE is Adaptive Multi-Rate Wideband (AMR-WB), also known as HD Voice. This codec is mandated in 3GPP networks that support 16 kHz sampling.^[57]

Fraunhofer IIS has proposed and demonstrated "Full-HD Voice", an implementation of the AAC-ELD (Advanced Audio Coding – Enhanced Low Delay) codec for LTE handsets. Where previous cell phone voice codecs only supported frequencies up to 3.5 kHz and upcoming wideband audio services branded as HD Voice up to 7 kHz, Full-HD Voice supports the entire bandwidth range from 20 Hz to 20 kHz. For end-to-end Full-HD Voice calls to succeed however, both the caller and recipient's handsets as well as networks have to support the feature.^[58]

See also

• LTE
• Wideband audio
• Video over LTE
• QoS Class Identifier (QCI) - the mechanism used in VoLTE networks to allocate proper Quality of Service to bearer traffic

References

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38. https://www.mylyf.com/earth-1
39. https://www.mylyf.com/water-1
40. https://www.mylyf.com/water-2
41. https://www.mylyf.com/wind-6
42. https://www.mylyf.com/flame-1
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