The VoWiFi landscape

Telecommunication Operators have always struggled to achieve 100% coverage, and to provide basic services like voice and text everywhere. LTE networks are beginning to be a reality but the increase in spectrum and network efficiency will not solve the in-building coverage problems especially in high-frequencies starting from 1.8 GHz. In this scenario of poor indoor coverage, voice over Wi-Fi became part of the Operator’s agendas for the past years and will continue to be with VoLTE.

Faced with the lack of effective and quick solutions from operators, subscribers usually solve their coverage problem by using OTT services like Skype or Viber. These OTT applications used to be a niche novelty but in the past few years started to be a serious threat to Telecommunication Operators. According to a recent study by Fortune, telecom companies count $386 billion in lost revenue to Skype and other OTT apps.

Telecommunication Operators have always striven to protect their voice revenues, including revenues from roaming. This has been the key argument for not adopting a voice over Wi-Fi approach, even when the technology became available. Times have changed, and since iOS8 shipped with native support for VoWiFi, subscriber demand for this service has increased. Some Android models also bring native support, but this is not widespread on these devices.

T-Mobile in the US has launched a Wi-Fi Calling solution back in September 2014. Other operators are taking similar approaches (like EE in the UK), allowing users to make and receive voice and text communications while connected to a Wi-Fi network. However, operators that have launched voice over Wi-Fi struggle to reach all their subscribers as only a few device manufacturers are currently supporting Wi-Fi Calling, on a limited set of devices from their portfolio. And take-up is dependent upon handset replacement cycles.

Most recently, GSMA Universal Profile, supported by Google, to unify the regional variances of RCS and to accelerate the mass-market reach of RCS in all Android devices. Whilst not aiming to extend the feature set of RCS, Universal Profile will simplify, unify and lay the foundation for future A2P BOT services to be offered to RCS communities.

The WIT VoWifi solution addresses this by:

  • Providing downloadable Android VoWiFi app;.
  • That connects through the EPDG using a secure IPSec tunnel;
  • Allows the user to choose the Wi-Fi networks on which they wish to make and receive calls.

Beyond the scope of this solution description, the WIT VoWiFi solution can be extended to tablets, PC and web end-points.

VoWiFi Interface

  • Modern UI
  • Intuitive and Easy to Use
  • Integrated with Local Contacts
  • Follows Operating System Guidelines
Whitelist Wi-Fi Network

User selects the trusted Wi-Fi networks to use the service.

App registers automatically for VoIP-in and SMS-in when entering whitelisted Wi-Fi networks.

Connection to ePDG

IPSec tunnel between WIT Apps and the ePDG using EAP-TLS.

Use certificates to remove the dependency on SIM authentication, allowing SIM-less devices.

VoIP in

User receives calls inside the App when connected to Wi-Fi.

Rings sequentially or in parallel on all user devices.

VoIP out

App initiated calls are routed to the CS Network.

User continues to make calls from a phone without cellular network coverage.

User can also make calls from the PC, Tablet and Web browser.

Multi-device VoWiFi

iPhone, Android, iPad, Android Tablet, Windows, Mac and all Web browsers.

Handover from Wi-Fi to 3G

Leverage existing DR-VCC capabilities on the network.

Provide call continuity from VoWiFi app to the native dialler.

SMS in

WCAS registers message copy in the SMSC.

SMS is received in all registered user devices.

Android App is able to intercept native SMS.

SMS out

Send text messages from a phone even without cellular network coverage, by using a Wi-Fi hotspot.

Send text messages also from the PC, Tablet and Web browser.

Devices using the VoWiFi App on iPad, iPhone and Android

Voice Calling using Wi-Fi on every device

Available for iOS, Android, Windows, MacOS and all web browsers.

Deployment of VoWiFi

VoWiFi can be deployed in two main options – On a Pre-IMS network or on an IMS Network

VoWiFi on a Pre IMS Network Diagram

WCAS integrates with the SMSC to ensure delivery and reception of SMS messages. The application server also sets the HLR and SCP for an accurate routing of calls.

The solution includes a WebRTC Gateway for web end-points, a Network Address Book and a Common Message Store for a multi-device experience.

  • Standalone Application Server
  • 3rd party SBC and Load Balancer
  • Auto-Configuration Server
  • Common Message Store
  • Network Address Book
  • WebRTC Gateway
  • Integration with SMSC
  • Integration with Media Gateway
VoWiFi on an IMS Network Diagram

VoWiFi Apps connect directly to the IMS Core. Web end-points connect through the WebRTC Gateway.

The IMS Core is responsible for routing both SMS and calls to the Apps when needed.

  • ISC Interface
  • Handles 3rd party Registration
  • Auto-Configuration Server
  • Common Message Store
  • Network Address Book
  • WebRTC Gateway
Operators’ Challenges

VoWiFi solves real problems

  • Cellular networks are rapidly becoming saturated.
  • LTE will not solve in-building coverage problems.
  • Subscribers prefer to use Skype when roaming abroad.
  • Native Wi-Fi Calling will not work in SIM-less devices.

WIT VoWiFi can also include Video Calling capability, allowing MNOs to launch a high quality video calling service without the dependency on ViLTE devices, as a way to counteract Apple Facetime and WhatsApp Video Calling.

Hand holding an iPhone, where the screen says that there is no SIM card installed
ommunication tower on snowy mountain against stormy sky background in difficult alpine terrainFixed Phone on Desk

Benefits for Mobile Operators

  • Offload traffic from cellular network to Wi-Fi.
  • Increase network coverage.
  • Reduce cost in femtocells or repeaters.
  • Increase customer satisfaction.
  • Offer an alternative to Skype, and use tariff minutes.

WIT VoWiFi can also include Video Calling capability, allowing MNOs to launch a high quality video calling service without the dependency on ViLTE devices, as a way to counteract Apple Facetime and WhatsApp Video Calling.

Fixed Phone on Desk

Benefits for Fixed Line Operators

  • Extend the value of the fixed line number by extending the reach to mobile devices.
  • Start the convergence of fixed and mobile networks.
  • Maximize calls quality by choosing the highest rated Wi-Fi network.

Benefits for Subscribers

  • No more need to rely on Skype
  • No more network coverage problems
  • Calls and messages across multiple devices
  • Ability to call anyone and be reached anywhere with own phone number

Interested on knowing more about our VoWiFi solutions? Check out our detailed PDF or get in touch with us.