AAA & Access Management – VoWiFi

In previous articles we have talked about the critical nature of AAA / Access Manager and why the functions remain at the core of telecom services. Enabling Voice over Wi-Fi for a telecom operator is a case in point; this is also called Wi-Fi Calling, but for the rest of this article the label VoWiFi is used. At a simple level it enables telephony services over available Wi-Fi access points. In effect, Wi-Fi Calling links telephony from a telecom operator to an internet environment, so you can mak e, answer, and maintain calls seamlessly when moving in and out of Wi-Fi and mobile networks.

VoWifi provides for low-cost coverage expansion of voice communications for Telcos to create and maintain reliable voice connectivity using pre-existing Wi-Fi access/IP connectivity. It is complementary to voice over LTE (VoLTE) but different, in that it uses Wi-Fi access points not LTE. The business case for this is driven by:

  • Necessity – disabling older circuit switched technology
  • maintaining quality of experience for voice calls
  • creating new service offers such as sponsored roaming.

In a world of apps, it may seem old fashioned, but making a phone call (and expecting it connect reliably and with quality) is still what customers do. A USwitch[1] survey in the UK rated phone calls as the third most popular activity (73%) (just behind messaging (78%) & email (74%)). Long call or short call it doesn’t matter – if the call quality is bad, users blame the network and there is plenty of choice if they want to switch networks. Voice quality and coverage is also a key factor on network assessment with leaders in testing like Umlaut[2] in their ‘Walk tests’ in big cities, or RootMetrics Call Performance tests.[3] Further, it can also be a misconception that coverage issues will be fixed by 5G – as 5G is a mix of radio technologies and pure 5G frequencies can be more affected in dense urban areas.

The voice use case matters for a third reason – a strategy to provide more capacity cost effectively is needed to meet the increasing data demands of the network. An integrated Wi-Fi solution is a building block of that strategy, in urban scenarios; data follows voice and integrating access for mobile and IP networks provides seamless, cost effective, capacity expansion.

The core case for VoWiFi is maintaining the quality of connection. In areas where circuit switched is being disconnected it is essential to link IPv4/IPv6 IMS to HSS authentication and this the role played by the AAA / Access Manager. Working in collaboration with a Telcos’ entitlement services, on device application and packet gateways the access management authenticates the IP telecom access for a voice call using the SWa | SWm diameter protocol to the request received from the evolved packet gateway (ePDG). The response from access manager contains the right authorization and additional attributes so that access is authorized. The additional attributes can be used to create different offers based on geo location and sponsored data/voice roaming for example – enabling new monetization options.

What Enea is doing is solving this use case and more across AAA / Access Manager deployments directly and with our partners. Enea provides AAA / Access Manager as virtualized software (VNF | CNF) increasing the cost benefit of capacity expansion for VoWiFi. The Access Manager has been deployed in more than 40 Operator networks including several large Tier 1 Telecom Operators. It has demonstrable interoperability across a wide range of interfaces and solution use cases.

For more information


[1] USwitch Survey 2023 –

[2] Vodafone Umlaut tests

[3] RootMetrics – UK test:

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