Wifi Calling Overview
With the arrival of the 4G mobile network, an all IP network, voice / SMS services were first offered by reusing the 2G / 3G circuit network. This is the Circuit Switched Fallback (CSFB) solution. However, this solution presents limitations that militate to offer voice over IP directly from the 4G network. This is the successor VoLTE service to CSFB. The customer can continue his mobile data sessions (Internet sessions) and at the same time call or be called. The 4G mobile core data network has evolved to support non-3GPP WiFi-type access, which allows the operator to densify its network at a lower cost even by using any public WiFi hotspot (non-trusted WiFi).
• The WiFi Calling service is certainly the main service that will be offered in this context of WiFi access connected to the 4G mobile data core network.
Moreover, WiFi Calling and VoLTE share the same service architecture (namely IMS, IP Multimedia Subsystem). An operator with the same IMS can therefore offer VoLTE (Voice over IP over LTE), ViLTE (Video over IP over LTE), WiFi Calling and RCS (Rich Communication Suite) services.
• With this service, users will no longer have to experience voice restrictions in areas without mobile coverage as they can now access voice services even inside buildings where reception is bad or in the event of a momentary peak in traffic. WiFi calling allows mobile voice calls to pass through the fixed broadband connection via WiFi access. For operators, this translates into a reduction in the termination rate due to insufficient coverage and capacity inside buildings.
Advantages
The WiFi Calling service allows mobile voice calls to pass through the fixed broadband connection via WiFi access. Among the advantages are:
Call or be called even without mobile coverage or when mobile coverage is poor as long as WiFi coverage is available.
Native VoWiFi client in the terminal. No application is to be installed. This is the same MSISDN number as in the case of VoLTE
Mobility management and handover management between VoLTE and VoWiFi and vice versa. On the other hand, SR-VCC is not possible but DR-VCC (Dual-Radio Voice Call Continuity) is to guarantee the continuity of the call from the VoWiFi world to the mobile circuit world.
Access all telephony services, including complimentary services, SMS, USSD, emergency call, CAMEL services, voice mail, via the IMS architecture common with VoLTE / ViLTE.
Replace the 3G or 4G femtocell solution, at a lower cost, especially for customers who do not have mobile coverage in their residence with the operator (This is the first reason why a customer changes operator). The operator very often funds femtocell equipment.
Call with lower communication costs than with mobile radio
Many mobiles on the market already support the feature like iPhone 5c, iPhone 5S, iPhone 6, iPhone 6S, Samsung Galaxy S5, Samsung Galaxy S6, Samsung Galaxy S6 Edge, Samsung Galaxy Note 4, the Sony Xperia Z3, etc.
The fact that iPhone supports VoWiFi is a very important driver for VoWiFi. The first countries where VoWiFi will be deployed are those with a strong penetration of smartphones and WiFi hotspots.
VoWiFi solves the problems of insufficient coverage during the initial phase of VoLTE deployment, reduces the cost of air interface rental by MVNOs and provides cost-effective international roaming services. In addition, mobile operators are attracting more subscribers using VoWiFi or retaining subscribers using competitive packages to increase their revenues and improve their competitiveness.
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