Wondering what to do about pricey cell phone calls? Struggling with data caps and throttling? Mired in an area with patchy cellular service? Consider Wi-Fi calling, available for both Android and iOS Smartphones. It’s a free service over a Wi-Fi connection when making or receiving calls from the U.S., Puerto Rico and the U.S. Virgin Islands. (International rates still apply for international calls.) Wi-Fi calling is similar to regular calling in that it uses “regular” or North American Numbering Plan (NANP) phone numbers.
Traditional wireless carriers like Verizon and AT&T sell a month’s worth of data usage at a bulk rate. God forbid that you should exceed your monthly data usage allowance. We’ve all heard horror stories about how someone’s kid started gaming on his SmartPhone and ran up exorbitant data charges rivaling the dollar amount of the monthly home mortgage. Now that Pokémon Go is the latest rage, it’s just another way for the kids to burst the data cap (and their parents’ bank account) on their mobile devices.
Welcome to Fixed-Mobile Convergence
Fortunately, in an attempt to unclog the airwaves, SmartPhones nowadays come with Fixed-Mobile Convergence (FMC) — the ability to use both cellular and Wi-Fi parts of the radio spectrum. When using either cellular or Wi-Fi, the switch to the other is seamless with no perceptible disruption in service. (FMC does a lot more than smoothly transition between cellular and Wi-Fi, but that’s a topic for another time.) One of the challenges facing FMC is handing off calls between cellular and Wi-Fi. Each uses a different ways to relay data — circuit switching and packet switching. In a circuit switched network (cellular), an electrical path is established between two points and the circuit is kept open until closed. Packet switching (Wi-Fi), on the other hand, transmits and receives data in the form of packets. Divitas Networks, among others, pioneered the development of cell phone software for seamless cellular-Wi-Fi handoffs.
More than One Standard to Skin a Technologic Cat
One strategy to relieve the congestion of cellular networks is the extension of the Wi-Fi network to the outdoor cellular environment. The World Interoperability for Microwave Access (WiMax) is basically Wi-Fi over distances that rival cellular coverage. The technology is based on IEEE 802.16 standards for broadband wireless access (BWA) networks. WiMax functions similarly to Wi-Fi but at higher speeds over greater distances for more users. Supposedly it has the capability to provide coverage even in areas hardwire infrastructure has trouble reaching while overcoming the physical limitations of a legacy hardwire plant.
Another standard, IEEE 802.21, approaches the challenges of handoffs between networks through Media Independent Handover (MIH). Certain applications pose bigger technological hurdles for convergence than others. For example, downloading a web page is relatively simple, occurs quickly, and so handoffs between networks are generally straightforward if necessary at all. But streaming a movie requires a number of progressions, viz the device recognizes signal loss, finds another network (perhaps among several) and connects to new network — all done seamlessly and without service degradation. MIH software performs this task, thereby delivering mobility to the device user.
See this video from the 2015 TIA Network of the Future Conference discuss Wi-Fi calling:
Wi-Fi Calling in the Real World
Of course Wi-Fi calling in the guise of VoIP has been around for a while. Services like Skype and WhatsApp are used across the world, oftentimes for free. What makes true Wi-Fi calling different is that no app or contact list is needed; it’s part and parcel of a phone’s native dialer. It can be defaulted as your phone’s primary mode of placing a call or it can be used to switch to Wi-Fi should a cellular signal falter.
Sometimes one does get what one pays for. Sound quality on Wi-Fi calls can suffer from variable bandwidth, and signal strength is further diminished as more people attempt to access the same network. And users may experience a one or two second “lag” or delay in an online conversation, which can make communication difficult, particularly if one is struggling to understand an unfamiliar accent from another part of the globe. For a decent quality call, expect to need a minimum of 1 Mbps bandwidth. Republic Wireless (more on them below) claims it can “hold” a call using 80 kbps, but quality suffers and calls may be dropped.
Alternative Wi-Fi Carriers
Below are some of the better-known alternative Wi-Fi carriers serving the U.S. Note that unlike major players such as Verizon or AT&T, they don’t require contracts, long-term or otherwise, to use their services.
Project Fi: In April 2015 Google rolled out Project Fi, their eagerly awaited wireless service for the U.S. Perhaps the most attractive part of Project Fi is that Google only charges for the amount of data customers use on their phones. As noted previously, Verizon and AT&T charge customers a bulk rate for a preset amount of data. Currently the service is only available on the Google Nexus 6 SmartPhone and is invite-only. Google piggybacks as a Mobile Virtual Network Operator (MVNO) on Sprint and T-Mobile networks.
Scratch Wireless: Operating as a MVNO on Sprint’s nationwide network, Scratch as of April of 2016 is no longer accepting new customers as “it works on unspecified new products and services.” Scratch Wireless CEO and co-founder Alan Berrey admitted that his company has faced difficulties promoting the Wi-Fi MVNO service model. Scratch was among the first MVNOs in the U.S. to carry network traffic principally over Wi-Fi networks, using the Sprint network only when Wi-Fi was unavailable.
Let’s be frank; Wi-Fi calling is supported by major cellular carriers because it’s the easiest way for them to offramp their network traffic and expand coverage without paying for costly infrastructure upgrades. All major carriers including Verizon, AT&T, Sprint and T-Mobile support Wi-Fi calling on a variety of devices using Android and iOS platforms. Brands and models include Samsung Galaxy S6 and S7, the LG G4 and G5, the HTC 10 and iPhone models 5C, 5S, 6 6s and 6s Plus. Check with carriers for details. For example, note that as of mid-June 2016, Sprint supported Wi-Fi calling on the iPhone 5C and 5S; AT&T and Verizon did not. Verizon supported Wi-Fi calling on LG G4; T-Mobile did not.