What is VoWiFi — and why are operators still investing in Wi-Fi calling?

VoWiFi uses IMS technology to provide a packet voice service delivered over IP via a Wi-Fi network

In sum – what to know:

Core element — VoWiFi is a key part of telco voice strategies, helping extend coverage, improving indoor performance, and supporting consistent voice services.

Accelerating demand – Demand for VoWiFi is accelerating, driven by the need for reliable, cost-effective voice in areas where cellular coverage is limited or inconsistent.

5G VoWiFi – 5G strengthens VoWiFi’s role rather than replacing it, enabling tighter integration with cloud-native cores, VoLTE and VoNR interworking, and new use cases.

India’s Bharat Sanchar Nigam Limited (BSNL) recently launched Wi-Fi calling or Voice over Wi-Fi (VoWiFi) services across India to support users in areas without or with limited mobile signals.

BSNL is not alone in launching such a service. VoWiFi is already a popular choice for many telcos around the world looking to bolster their connectivity offers, but what exactly is this technology, who benefits, and what is driving demand?

What is VoWiFi?

A complementary technology to VoLTE, VoWiFi uses IMS technology to provide a packet voice service delivered over IP via a Wi-Fi network. In ideal conditions, voice sessions can be seamlessly handed over between LTE and Wi-Fi networks.

According to the GSMA, VoWiFi benefits both end-users and operators. For consumers, this technology enables them to make calls without the need for a mobile signal — particularly valuable in remote locations. They will also benefit from security based on SIM-based authentication, as well as improved indoor coverage.

For operators, VoWiFi can unlock revenue opportunities and lead to a competitive advantage. They can also leverage existing VoLTE SIM-based security and authentication and access IMS-based services via Wi-Fi access.

Growing demand for VoLTE and voice over Wi-Fi in U.S.

In the U.S., all three major carriers offer Wi-Fi calling, and have for years. However, a recent report found that demand for VoLTE and VoWiFi services in the country is projected to rise sharply, growing from $3.2 billion in 2026 to $29.6 billion by 2036, a compound annual growth rate of 22.4%. The rate of growth is expected to accelerate as the adoption of 5G and Wi-Fi calling expands.

The biggest driver behind this rise in demand, stated the report, is the increasing need for high-quality, cost-effective voice services in mobile communication. “As mobile data networks evolve, VoLTE and Voice Over Wi-Fi offer clear voice calls with better connectivity and coverage, especially in areas where cellular signals are weak,” it said. “As mobile data consumption rises and 5G adoption increases, VoLTE and Voice Over Wi-Fi are becoming essential components of modern communication networks.”

The increasing penetration of 4G and 5G networks — which enable faster and more efficient voice services — is also behind the growth in demand, as well as the widespread availability of Wi-Fi in public spaces and homes.

Beyond the U.S., Bell, Telus, Rogers, Fido, and Virgin Mobile in Canada all support Wi-Fi calling, as do Orange and Bouygues in France, O2, Telekom, and Vodafone in Germany, and AIS in Thailand, just to name a few.

What about 5G VoWiFi?

Despite the rise of 5G, VoWiFi remains a core component of operators’ voice strategies — and in some cases becomes more important, not less. A common misconception is that “5G VoWiFi” represents a new radio technology. In practice, VoWiFi continues to rely on the same IMS-based architecture used for VoLTE, with Wi-Fi serving as the access network rather than cellular spectrum.

What 5G does change is the operational environment around voice services. In standalone (SA) 5G networks, operators can more tightly integrate VoWiFi with cloud-native cores, network slicing, and policy control, enabling more consistent quality of service across access types. This allows voice sessions to move more seamlessly between 5G, LTE, and Wi-Fi while maintaining reliability, security, and low latency.

In a 2025 white paper, the GSMA noted that the evolution toward 5G is introducing new requirements for Wi-Fi calling. These include closer interworking with both VoLTE and 5G Voice over New Radio (VoNR), as well as support for additional IMS services beyond voice, such as data channels. Wi-Fi calling is also expected to play a growing role in delivering voice, video, and messaging services over satellite backhaul in maritime and in-flight connectivity scenarios.

From a network architecture perspective, the industry is still in transition. While many operators initially deployed legacy evolved Packet Data Gateways (ePDGs) to connect Wi-Fi calling traffic into the 5G core, the GSMA recommends migrating toward native non-3GPP interworking functions (N3IWF) to take full advantage of 5G security frameworks and unified authentication models. Challenges remain, including accurate location determination when Wi-Fi access networks are owned by third parties or connected via satellite, as well as inconsistent support for end-to-end QoS marking in some devices and consumer Wi-Fi equipment.

Taken together, these developments reinforce VoWiFi’s ongoing relevance in a 5G era. Rather than being displaced, Wi-Fi calling is increasingly positioned as a foundational element of converged voice strategies, enabling operators to deliver consistent services across heterogeneous and complementary wireless networks.