Chapter 1
The Evolving Voice Services: From Circuit Switching to Voice-Over LTE/FTTH)
Voice is the most pervasive telecommunication service, particularly mobile voice, with 4.7 billion unique mobile subscribers as of April 2016,1 out of a total 7.8 billion mobile connections. Legacy circuit switched voice still accounts for majority of world telecom customers; however, voice-over IP is finally starting to replace it. Voice-over IP technologies such as H.323, Session Initiation Protocol (SIP), and voice codecs including wideband, carrier grade infrastructure known as IMS-IP Multimedia Subsystem2 have been available for more than a decade, but deployment of All-IP access networks (FTTH (Fiber-to-the-Home) and LTE (Long-Term Evolution)) has been the trigger for their adoption. Only in the enterprise segment, the legacy PBX systems have initiated the migration earlier. In fixed networks, initial FTTH deployments maintained simultaneous use of legacy copper for voice. In 4G mobile networks, fallback to 2G/3G for voice has been a temporary patch until VoLTE deployment in the network and progressive availability of enabled devices. HD Voice is included in VoLTE, but is also available in 3G networks without VoIP. Voice-over WiFi is emerging as a complement mainly for zones with poor cellular coverage.
1.1 Customer Need: Remote Communication
Voice has been the dominant, or even only, telecommunications service for decades. The possibility of talking to people in remote places has been, and still is, a killer application. It has substituted more primitive means to communicate, both non-real-time and real-time. Furthermore, the convenience of talking wherever you are, thanks to the more recent mobile telephony that has certainly surpassed the success of fixed telephony, allows one to communicate in more remote areas without terrestrial infrastructure.
1.2 FTTH Voice
The penetration of FTTH subscribers is still nascent; for example, in Europe there were almost 36 million (including Fiber to the Building) in Europe at the end of September 2015.3 This has triggered the adoption of voice-over IP in fixed lines, although initial FTTH deployments supported simultaneous use of legacy copper for voice. Typically, the FTTH customer premises equipment, Optical Network Terminal (ONT), includes a voice port (RJ-11 connector) that interfaces with the legacy internal copper network or directly with the legacy telephony terminal. The usage is transparent for customers, since they make and receive calls normally with their legacy endpoints. The FTTH device includes a gateway that converts analog telephony into voice-over IP, which in turn is connected to the VoIP infrastructure of the operator.
1.3 Voice-Over LTE (VoLTE)
Voice-over LTE is the name given to the technology that provides telephony to 4G customers. It is based on voice-over IP, since LTE gets rid of circuit switched voice. In order to guarantee voice quality, VoLTE traffic is prioritized versus other kinds of traffic, which is also IP. Initial LTE deployments did not include VoLTE support, resorting to Circuit Switched FallBack (CSFB), which is based on disconnecting voice from the 4G network and connecting it to a legacy network (3G or even 2G) to establish the voice call. Once the call is finished, 4G connection can be set up again.
As of the end of the first quarter of 2016, there were 58 operator launches, in 32 countries,4 with 228 end user devices. This was still a relatively small percentage of the total number of LTE networks: 467 operators in 153 countries, reaching 48% of the population. As could be expected, these countries are mainly in Europe, North America, South East Asia, and Oceania:
- Asia Pacific:
- – Japan by NTT Docomo, KDDI, and Softbank (the “big three”)
- – South Korea by Korea Telekom (KT/KT Powertel), SK Telekom, and LG Uplus
- – Hong Kong by China Mobile, 3 (Hutchinson), CSL (HKT), and SmarTone
- – Singapore by SingTel, StarHub, and M1
- – Taiwan by Hon Hai, Asia Pacific Telecom, and Taiwan Mobile
- – Australia by Telstra and Vodafone
- – China by China Unicom and China Mobile (not China Telecom)
- – Others: Indonesia by XL (Axiata) and SmartFren; Thailand by AIS, TrueMove, and Telenor (DTAC); Kuwait by KTC; Cambodia by Southeast Asia Telecom, and others
- Europe:
- – France by Bouygues and Orange
- – Germany by Deutsche Telekom, Telefonica,5 and Vodafone (all three mobile network operators)
- – Italy by Telecom Italia and Vodafone
- – The United Kingdom by 3 (Hutchinson) and Everything Everywhere (BT)
- – Spain by Vodafone6
- – Others: Austria by Telekom Austria; Czech Republic by Deutsche Telekom; Denmark and Norway by Telenor; Switzerland and Liechtenstein by Swisscom; The Netherlands by Tele2; Portugal by Vodafone; Romania by Orange7; Russian Federation by Vimpelcom, and others
- North America
- – The United States by AT&T, Deutsche Telekom, Verizon Wireless, and Evolve Broadband (big four except Sprint-Softbank)
- – Canada by Rogers and Bell
- Africa: Tanzania, Uganda, and Nigeria by Smile; South Africa by Vodacom (Vodafone)…
It can be seen that all major mobile telecommunication groups in the world have launched VoLTE in at least one market. Among the exceptions are
- America Movil in Latin America
- Etisalat and Saudi Telecom in Middle East
- China Telecom in China
- Bharti Airtel in India
- Telekomunikasi Indonesia and Chungwa Telecom in Asia
- Telia in Europe
- MTN in Africa
- Telus in Canada
- …
However, it has to be note...
