Voice over 4G networks. LTE: from Tests to Implementation

April 2013

Analytical Report (full version)

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Analytical Report (full version)

Voice over 4G networks. LTE: from Tests to Implementation
Voice over 4G networks. LTE: from Tests to Implementation
April 2013

Voice over 4G networks. LTE: from Tests to Implementation

April 2013

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J’son & Partners Consulting presents the results of the research “Voice over 4G networks. LTE: from Tests to Implementation.”


LTE Networks and Traditional Mobile Services

Mobile communications networks based on the LTE standard, developed by the 3GPP Consortium for high-speed data communication, are at the stage of active global deployment. According to GSA, from December, 2009, when the first commercial LTE network was launched, to the middle of March, 2013, the amount of commercial LTE networks in 67 countries reached 156 and 412 operators in 125 countries invested in the technology. It is forecasted that 244 commercial LTE networks will be deployed in 87 countries by the end of 2013.


The LTE ecosystem evolves rapidly. It is anticipated that by the end of 2013, some 300 various models of LTE-compatible terminal devices will be available on the market. According to GSMA’s forecast, the number of LTE-compatible smartphones in use will grow to 920 million by 2017, up from 62 million as of the end of 2012. At the same time, there is a significant amount of smartphones on the today’s market that can operate only on 2G and 3G networks; their quantity is estimated 1.9 billion by the end of 2013.


A critical issue for the spread of LTE is the support of traditional services, namely telephony and SMS, which still bring most of mobile operators’ revenues. LTE networks belong to All-IP-class (“all over IP”) networks, utilizing the principle of packet switching on every section of the network. For this reason, the LTE technology is not meant for supporting “voice” and SMS the way it is realized on switched 2G and 3G networks. Thus, the implementation of VoLTE (Voice over Long Term Evolution), a communication of voice over an LTE network, is one of the most urgent tasks for mobile operators implementing the 4G technology on their networks.

In 2013, the revenues from voice services will amount, according to GSMA, over 60% of operators’ revenues; therefore, providing the support of voice services on LTE networks becomes a topical problem. However, the implementation of VoLTE will be not so quick, as against the growth rates of commercial LTE networks.

VoLTE Definition and Status

The VoLTE initiative (originally, “One Voice”) was formally announced by the GSM Association on February 15, 2010 and is aimed to standardize the methods of communicating voice and SMS over LTE networks. As its basis, the IMS (IP Multimedia Subsystem) specifications by 3GPP Consortium were used.


Operators hope that VoLTE will ensure the provision of voice services over a packet switching network characterized by a carrier-class quality, as opposed to VoIP services by third-party providers (so called OTT providers). On networks with VoLTE support, the subscribers may use, for example, such services as HD Voice and Rich Communication Services (RCS).


As of March, 2013, from 156 LTE networks operating worldwide, the support of VoLTE was implemented for only three of them – MetroPCS (the USA), SKT and LG U Plus (South Korea). Several other U.S. operators are planning to implement the technology by the end of 2013 – the beginning of 2014.

The main operators’ objective to implement VoLTE is the provision of voice services on 4G networks with a quality relevant/higher than traditional 2G/3G networks. To implement this technology, an operator should deploy IMS and build a LTE radio access network on its core network. Interim technologies on the way to VoLTE are CSFB, SRVCC and SVLTE.

In the medium term, the main drivers of implementing VoLTE in Russia will be the following: spread of smartphones featuring LTE support, widening of the 4G coverage and increasing pressure from OTT services.

The typical strategy of an operator for implementing voice services on LTE networks involves implementing an “interim” CSFB technology with a gradual transition to IMS and VoIP. Until the national LTE coverage is ensured, the SR-VCC (Single Radio Call Connectivity) technology will be used. When a subscriber leaves the VoIP coverage area, SR-VCC provides transition from IMS based VoIP to circuit-switched (CS) voice and vice versa. The final stage is the implementation of a full-fledged IMS platform and transition of all calls to packet networks (IMS based VoIP). 

VoLTE-Compatible Devices

As of March, 2013, less than 10 models of subscriber devices compatible with this technology are used in the countries which implemented VoLTE in August, 2012 (the USA and South Korea). It is expected that, as VoLTE spreads, the model range will be considerably expanded.


Nowadays, VoLTE support is realized on a limited number of models of smartphones. This is one of the main constraints for this technology development, and it will be overcome in the medium term.

Forecasts and Prospects

According to ARChart, the VoLTE market will experience a significant growth in the coming years. About 2 million devices with VoLTE support are expected to be sold in 2013 (mainly, in the USA and South Korea), the revenues from VoLTE services reaching approximately $56 million. It is forecasted that the number of VoLTE users will amount 70 million by the end of 2016 (about 10% of LTE users). According to Infonetics Research, by 2016, the share of VoLTE on the VoIP service market will be 14%, which means that the lion’s share of VoIP will remain under the control of OTT. The Signals and Systems Telecom Company predicts LTE equipment industry’s growth with the compound annual growth rate (CAGR) being approximately 150% in 2013 – 2016.

Analysts claim that the number of OTT and VoLTE services users will increase several times by 2016, but nonetheless, the number of 2G and 3G networks subscribers will predominate as before. In the medium term, the VoLTE market will remain a niche one, accounting for 1/7th of the revenues on the VoIP market.

List of contents of the Full Version of the Report “Voice over 4G Networks. LTE: from Tests to Implementation”


List of Contents of the Report

       1.1. Market of mobile communication traditional services: main threats and solution
              1.1.1. Revenue structure of the largest mobile network operators in Russia and in the world
                        – Voice and SMS
              1.1.2. OTT services threats: Mobile VoIP and MIM
              1.1.3. Rich Communication Services (RCS) as one of mobile network operators’ revenue
                        protection approaches
              1.1.4. Lessons from fixed (line) communications
       2.1. LTE as All IP technology
       2.2. Quality of service (QoS) as a technological advantage
       2.3. VoLTE and HD Voice
       3.1. VoLTE and IMS
       3.2. Alternative approaches
              3.2.1. CSFB (Circuit Switch FallBack)
              3.2.2. SRVCC (Single Radio Voice Call Continuity)
              3.2.3. Dual-Radio Handset
              3.2.4. VoLGA
       4.1. Commercial services
              4.1.1. SK Telecom
              4.1.2. LG U Plus
              4.1.3. MetroPCS
              4.1.4. Other operators
       4.2. VoLTE service testing and operators' plans
              4.2.1. Verizon Wireless
              4.2.2. AT&T Mobility
              4.2.3. Other operators
              4.2.4. Situation in Russia
       4.3. Support at the level of subscriber devices
              4.3.1. HD Voice (W-AMR)
              4.3.2. VoLTE
       5.1. In the world
              5.1.1. Limitations and compatibility issue
              5.1.2. Legislative limitations
              5.1.3. Other limitations
       5.2. In Russia
       6.1. Competition with OTT services
       6.2. Forecasts
              6.2.1. According to the number of VoLTE users in the world
              6.2.2. According to the VoLTE equipment market in the world
              7.1.1. Ericsson
              7.1.2. Nokia Siemens Networks
              7.1.3. Alcatel-Lucent
              7.1.4. Huawei
              7.1.5. ZTE
              7.1.6. Specialized providers of Voice-over-IMS solutions
Annex 1. Commercial LTE networks in the world


List of Figures

Fig. 1. Generalized architecture of mobile networks
Fig. 2. Dynamics of mobile operators’ operating revenue changes in the world
Fig. 3. Forecast of the growth of mobile communications voice and non-voice services until 2017
Fig. 4. Map of the RSC-e/JOYN project’s spread throughout the world, March 2013
Fig. 5. Compatibility of the digital cross-over switch (PBX) and NGN network archtectures
Fig. 6. Generalized architecture of networks, including LTE/EPC and NGN
Fig. 7. LTE/EPC architecture
Fig. 8. Separation of service and signalization flows on the LTE/EPC network
Fig. 9. Separation of service and signalization flows on the LTE/EPC network
Fig. 10. HTC Thunderbolt Dual-Radio terminal
Fig. 11. Possible ways of voice service provision on LTE networks
Fig. 12. Countries of the world with launched HD Voice
Fig. 13. The number of LTE subscribers (million) by operators in the world (2H 2012)
Fig. 14. Comparison of the coverages of 3G/LTE networks of Verizon and AT&T
Fig. 15. Growth in LTE subscribers on DoCoMo's network (2010 - 2013)
Fig. 16. EPC detailed diagram with access networks and IMS components
Fig. 17. One of solutions for E911 in VoLTE
Fig. 18. Power consumption comparison for CDMA and VoLTE modes
Fig. 19. Composition of the mobile networks subscriber base by 2016
Fig. 20. Composition of the mobile networks subscriber base by 2016 (OTT and VoLTE)


List of Tables

Table 1. Operating revenue from Russian mobile operators’ service provision, billion rubles*
Table 2. RCS SWOT analysis
Table 3. Comparison of LTE voice services implementation methods
Table 4. Networks with VoLTE support in the world
Table 5. Commercial LTE networks with VoLTE support
Table 6. VoLTE testing in the world
Table 7. VoLTE-compatible models of smartphones in the world as of March 2013
Table 8. Comparison of OTT services and VoLTE




This Information Note is Prepared by J’son & Partners Consulting, We strive to provide factual and prognostic data that fully reflect the situation and are available to us before issuing the material. J’son & Partners Consulting reserves the right to revise the data after publication of new official information by the market players.



J’son & Partners Consulting presents the results of the research “Voice over 4G networks. LTE: from Tests to Implementation.”