VoWiFi (Voice over Wi-Fi)

Voice over Wi-Fi delivers carrier voice service through the IMS over a Wi-Fi access network, using an ePDG and IPsec tunnel back into the operator core. Subscribers benefit from indoor coverage in poor-signal areas; security depends on IPsec authentication with EAP-AKA, integrity of the ePDG, and proper IMS access controls. VoWiFi reuses the same MSISDN and IMS identity as VoLTE/VoNR.

Categories: Radio Access NetworkCore NetworkIdentity and Subscriber

VoWiFi in context

The radio access network is the layer where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations, downgrade attacks and jamming, and defenses hinge on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

The mobile core is where subscriber sessions, mobility and policy live. In 4G it is the EPC (MME, HSS, S/PGW); in 5G it is the Service-Based Architecture with AMF, SMF, UPF, AUSF, UDM and the NRF. Core exposure is the difference between a single-subscriber leak and a fleet-wide breach.

To place VoWiFi in the wider telecom-security picture, review ePDG, MNO, FDD, UPF, VoLTE and Zero Trust (Telecom).

Related terms

Equipment

Wi-Fi and non-3GPP access gateways (ePDG, N3IWF, TWAG, TNGF)

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