Lost in the alphabet soup that is Google’s new holding company is one of its many experiments in changing the business rules for network services while nudging the technology in a direction that ultimately benefits consumers. No, not Fiber, although it’s a fantastic broadband disruptor for those that can get it, but Project Fi, Google’s mobile service. After arriving with great fanfare this spring, Fi has slipped under the radar because of Google’s slow, by-invitation rollout, its very limited phone support (one!) and the fact Google hasn’t publicized the service like its more sexy Project X experiments like Glass, Loon and Self-Driving Cars. Indeed, the individual pieces that make Fi appealing aren’t unique, but collectively they are trendsetting and could herald welcome changes in how we all use and pay for phones and wireless service.
At its core, Fi is just another MVNO (mobile virtual network operator) that combines Sprint and T-Mobile LTE networks into a hybrid that automatically uses the best available signal. But Fi takes the concept one step further by incorporating WiFi calling, what carriers term voice over WiFi (VoWiFi). In areas with no or very weak cell coverage, but strong WiFi signals the phone automatically switches over. Unlike OTT services such as WhatsApp or Viber, VoWiFi uses the native phone number, dialer and SMS client (Android Messenger or Hangouts in this case), but as with OTT, WiFi activity doesn’t cost you by counting towards Fi data usage.
The Fi meta-network is a great idea and well implemented, but not without limitations. Like all VoWiFi services, call handoff only works one way, from WiFi to LTE. According to an Ericsson white paper, handoff from calls initiated on LTE isn’t currently possible, but specifications are under development to support bi-directionality. Another issue with all VoWiFi implementations is the uncontrolled nature of most public WiFi networks that complicates the decision about if and when phones should automatically switch from cell to WiFi. Some carriers and large enterprises deploying WiFi for fixed mobile convergence (FMC) telephony systems opt for trusted WiFi access gateways (so-called TWAGs): hardware devices that combine features of an enterprise WiFi controller and carrier evolved Packet Data LTE gateway (ePDG, a bridge device providing secure delivery of mobile packet services over untrusted networks). Like WiFi controllers, TWAGs aggregate traffic from multiple APs, authenticate the hotspot and build a secure tunnel to the carrier’s core network, apply some QoS traffic shaping, authenticate devices and collect usage statistics.
While secure and reliable, TWAGs are an added hardware and management expense Google obviously wanted to avoid. Instead, Fi uses a combination of Android’s WiFi Assistant app and a database of known, vetted and reliable public hotspots to set up automatic connections. Remembering how insecure public WiFi can be, Google completes the setup by establishing a VPN from the phone to its core network that protects all voice and data communications. The problem with Google’s approach is the seemingly manual nature, although the company hasn’t offered details on how hotspots are vetted nor a public process for submitting WiFi networks for inclusion in the trusted Fi ecosystem. Lacking a known hotspot Fi phones default to cellular, even if it’s not LTE. Of course, resourceful users can for WiFi calling by putting the phone into airplane mode (which disables all radios), manually re-enabling WiFi and connecting to an available network. All the VoWiFi features work, even on a protected network, but the process is sufficiently inconvenient that few users will bother.
The other problem with Fi is a dearth of device choice: channeling Henry Ford, Google’s initial implementation allows you to use any phone you want as long as it’s a Nexus 6. Now, the Nexus 6 is a great flagship phone, particularly if you like screen real estate, but with a giant 6-inch screen and footprint slightly larger than an iPhone 6 Plus, it’s not for everyone. This limitation will surely abate, as Google is expected to introduce two new Nexus models this fall and Fi’s technical requirements are no different than WiFi calling services available from other carriers where T-Mobile offers 18 different devices.
