Have you ever walked into the office or perhaps an area in your home with your mobile phone and tried to make a call, only to have poor LTE/4G/3G signal strength keep your callfromconnecting? What did you do? Well if you're like me, you probably wanted to throw your phone and revert back to the reliable, old land line. What if, instead of relying on the signal strength of your mobile service provider, you were to make voice calls over your home or office Wi-Fi network?

Mobile network traffic is growing exponentially, and service providers must manage their networks efficiently to meetconsumer demand. Long-Term Evolution (LTE) radio access is reaching the limits of Shannon's law (the maximum rate at which error-free digits can be transmitted over a bandwidth-limited channel in the presence of noise), the spectrum available for mobile data applications is limited, and the only solution for increasing overall mobile network capacity is to increase the carrier-to-interference ratio while decreasing cell size and deploying small cell technologies.

Wi-Fi, one of the most ubiquitous small cell technologies, appeals to many mobile operators as a cost-effective mean of offloading large amounts of mobile data traffic while delivering a variety of new services. It offers:

• Widespread existing deployments
• Availability of user devices that support the technology
• Cost efficiency
• Capability to address new users and devices without mobile subscription (without a subscriber identity module [SIM])
• Globally available spectrum capacity
• Standards availability for integration into mobile core networks

Voice over Wi-Fi (VoWi-Fi) is the use of a wireless broadband network for the purpose of vocal conversation. VoWi-Fi is becoming the industry standard for mobile service providers seeking to deliver voice and short message service/multimedia messaging service (SMS/MMS) over Wi-Fi. In fact, many smart phones today now come equipped with the option to make calls or send SMS messages over a Wi-Fi network and often default to this setting when Wi-Fi networks are available.

VoWi-Fi is going to surpass voice over LTE (VoLTE) by 2018 in terms of minutes of use. By 2019, VoWi-Fi will have 53 percent of mobile IP voice, up from less than a tenth of a percent in 2014, according to the Cisco Visual Networking Index. For service providers, Wi-Fi has become the preferred mobile data experience based on speed, cost and coverage. With VoWi-Fi, mobile subscribers receive a seamless voice and messaging experience as they move between the macro cellular network and existing Wi-Fi networks such as those at home and the office. To deliver a high-quality experience for high-definition (HD) voice and data services over Wi-Fi, service providers need performance, scale and services from an end-to-end solution that spans access, mobile core and telecommunication cloud.

Mobile operators can utilize evolved Packet Data Gateway (ePDG) technology solutions to provide the same service capabilities and consistency on the Wi-Fi network as is available on the macro network. This includes consistent Quality of Service (QoS) provided over the Wi-Fi network. The adoption and success of Wi-Fi offload solutions depends on the end-user experience that the solution delivers. End users will seek to preserve the quality of experience regardless of the access type. Quality of experience is typically defined as ease of connectivity, transparent authentication, and transparent services, while preserving the security of the macro cellular network.

Voice over Wi-Fi marks a new era for service providers, and Cisco is excited to work with service providers to capture this transformational shift. With a long history of Wi-Fi experience and strong presence in the mobile packet core, Cisco is well positioned to offer an industry-leading end-to-end solution for Wi-Fi offload. Cisco is committed to providing a Wi-Fi offload solution that is scalable, flexible, and ready for the upcoming industry evolution.

For questions or comments around VoWi-Fi, tweet us @CiscoSPMobility.