Carrier Wi-Fi Calling: Promises, Failure, Resurrection
Here's a look at why enterprise Wi-Fi networks will become the de facto medium for multimodal carrier traffic.
The path to mainstream acceptance of Wi-Fi calling is littered with speed bumps and false starts. So what's different this time around? The answer to this question requires us to revisit history and understand the mobile carrier's love/hate relationship with Wi-Fi.
A Little History, a Simpler Time
At the start of the current millennium, AT&T's Digital One Rate revolutionized cellular-minute economics, resulting in wireless calling for the masses. Dropping prices and improvements in digital coverage fueled landline displacement. User habits soon changed and cellular phone numbers became the primary-reach number for the new workforce.
As more subscribers cut the landline cord at home, carriers grappled with providing better indoor coverage and more capacity at venues where subscribers converged. By the second half of the decade, distributed antenna systems (DAS) appeared at strategically located public venues. Although incredibly expensive, they vastly improved coverage and capacity where needed.
Unfortunately, most private enterprises were left in the cold. Employees and guests had poor voice coverage in the workplace because enterprises didn't have the resources to fund a DAS solution or the right carrier relationships.
Carrier-supported femtocells that strengthened coverage at home would never scale for enterprise deployments. Meanwhile, enterprise Wi-Fi was just in its infancy. The service coordination, quality of service (QoS), and handsets needed to support Wi-Fi calling did not exist. In the end, only a small subset of facilities that absolutely needed cellular coverage were able to pony up the big bucks for DAS.
Those were simpler times, back in a day when voice was the main revenue center for carriers. But things were about to change very quickly.
It's 2007, Introducing the iPhone
The iPhone revolutionized mobile phones. They were no longer just telephones, but Internet computers in our pockets. Evident from Day 1 was that the cellular networks were the bottleneck. Mobile devices needed a more efficient and cheaper way to transfer data.
The iPhone was instrumental in kicking off two significant occurrences:
- Carriers begin an arms race to upgrade networks to 3G and later 4G to meet data demands and acquired massive amounts of licensed radio frequency (RF) spectrum along with way.
- Smartphones with dual-mode radios became available to support cellular and Wi-Fi.
As a result, Wi-Fi became many carriers' BFF for data offload. Without it, streaming media and unified communications wouldn't have been possible. It would enable all new possibilities for the mobile development community.
OTT and the Rise and Fall of UMA
With every new possibility comes the probability for disruption. Wi-Fi's pervasiveness across smartphones presented some interesting business opportunities for many technology startups. Over-the-top (OTT) voice/messaging applications like Skype and WhatsApp emerged nearly every other day. Almost overnight, Ma Bell's prized voice business model was no longer untouchable.
Fortunately for carriers, three things prevented OTT from fully displacing cellular:
- OTT required a non-native phone application along with a separate phone number.
- A lack of Wi-Fi QoS and poor inter-access point roaming contributed to an inconsistent call experience.
- Introduction of carrier unlimited voice plans eventually neutralized the main cost advantages of OTT.
Separately, alternative carriers like T-Mobile looked at OTT and started supporting a carrier Wi-Fi calling alternative called Unlicensed Mobile Access. UMA would encapsulate GSM voice packets for delivery over a Wi-Fi network back to the carrier itself.
As a result, users could make calls over Wi-Fi networks with the phone's native dialer and phone number. Despite its advantages, UMA was a commercial failure. Cellular providers viewed the delivery of voice services over Wi-Fi as a threat to their underlying business models. Mainstream carriers outside of T-Mobile wanted no part of this.
By the end of the decade, large carriers like Verizon had deep spectrum positions and much faster 3G networks. Why bother shipping calls over a network you didn't control? The first generation of carrier Wi-Fi calling was a bust -- the technology was too far ahead of its time.
LTE and the Resurrection
Fast forward to present day. Mobile data usage continues to grow exponentially and carriers are once again struggling to keep up. Wi-Fi calling is suddenly in vogue again. What's different this time and why will it succeed?
- Factor 1: Capacity - The need for data capacity has forced carriers to pull all the stops. Invest in faster technology, buy more spectrum, reharvest spectrum, buy more spectrum. As a result, carriers are dropping legacy technologies as fast as they can to reallocate the spectrum to LTE. However, carriers are still reliant on inefficient circuit-switched technologies (UMTS and CDMA) to service voice calls. Consequently, carriers must adopt voice over IP and voice-over-LTE (VoLTE) to free up spectrum for additional data capacity.
- Factor 2: Vendor support - Meanwhile the carrier service provider market is a cutthroat business. Subscriber acquisitions require poaching customers from the competition. In 2014, a reinvigorated T-Mobile dusted off an old marketing plan and went big again with Wi-Fi calling. This time backed up with meaningful technology from VoLTE and a stamp of approval from Apple with Wi-Fi calling support in iOS 8. Things are different this time around. Kingpins AT&T and Verizon quickly announced their intention to support Wi-Fi calling in 2015. And the rest is history.
- Factor 3: Indoor coverage - Indoor coverage is the only thing that can ensure that Wi-Fi calling succeeds this time around. It's simply too expensive to build a multicarrier DAS system that supports the numerous frequencies and protocols for the general-purpose office space. Add complex indoor interference challenges when combining multiple RF sources and you have a very expensive and hard-to-maintain solution. Back in the mid 2000s, we dealt with systems that fundamentally needed to support two bands (cellular and PCS) and maybe one or two technologies (CDMA/GSM). Today, the combinations are endless (CDMA/LTE/UMTS, cellular, PCS, AWS, 700 MHz, AWS-3, and low band) resulting in very complex DAS designs. Faster and faster data speeds dictate better signal-to-noise ratio coverage. Enterprise Wi-Fi will be the most logical way to deliver tomorrow's indoor carrier voice and data services.
What It Means For Us
As mobile strategists or corporate network operators, we need to familiarize ourselves with this important trend and prepare our internal Wi-Fi networks for the potential flood of Wi-Fi calling. It will force organizations to re-evaluate Wi-Fi network design, handoffs, QoS, and RF coverage goals.
So does this mean DAS systems are dead? Not by a long shot. There are plenty of places -- airports, stadiums, train stations and malls -- where DAS will be the network of choice for carrier services.
But for the vast amount of private real estate locations, Wi-Fi networks will become the de facto medium for multimodal carrier traffic and the costly DAS approach will fall by the wayside.
Alan Ni is head of vertical marketing at Aruba Networks.