Apple s iPhones 6 devices have a cool new calling feature, but how well it works — or even if it s available at all — depends on your carrier.
The new iPhone 6 models support a new calling standard called VoLTE, which stands for Voice over LTE (or long-term evolution). Basically, what the standard does is to send calls made with the phones built in dialer over the wireless carriers data networks. That change could eventually have some big advantages for both carriers and consumers, allowing for better quality calls and fewer dropped connections.
But in the near-term, the switch to VoLTE could mean a more frustrating experience for some consumers — assuming they can use the service at all.
Of the Big Four carriers, only T-Mobile and Verizon are promising nationwide VoLTE coverage. Verizon is offering VoLTE — which it calls Advanced Calling 1.0 — in all the markets in which it offers its high-speed LTE data service. T-Mobile is basically doing the same.
But even if you subscribe to one of those carriers and are in one of their LTE markets, your ability to make VoLTE calls will depend on whether you are connected to an LTE-supporting cell tower. If you re not, you can t make a VoLTE call, by definition. (On the iPhone, you can confirm that you are connected to an LTE tower by looking for the LTE logo next to the cellular antenna strength indicator in the upper-left hand corner of the screen.)
Of the other two big carriers, Sprint isn t yet offering VoLTE anywhere, and AT&T is only offering it in select areas in Illinois, Indiana, Minnesota, Wisconsin and Georgia, according to company spokesman Alexander Carey.
Even where you can get VoLTE, you may have a frustrating experience with it, especially if you are a Verizon customer. If you initiate a VoLTE call on Verizon and then move to an area that has a tower that doesn t support VoLTE, the call will drop, company spokeswoman Heidi Flato said. For now, Verizon iPhone 6 and 6 Plus users have to manually turn on VoLTE by going into their settings.
T-Mobile is supporting an advanced protocol that promises a seamless handoff between the VoLTE system and its older voice network when callers move from an LTE-supporting tower to a non-LTE one, said Rich Garwood, the company s Northwest Area vice president. Similarly, on AT&T, calls made over VoLTE switch over to standard voice calls when users move from LTE to non-LTE towers, Carey said.
One good thing to note about VoLTE calls. Even though such calls are being sent over the carriers data networks, they won t count toward users data caps — at least not right now. Verizon, AT&T and T-Mobile all say that they are treating VoLTE calls just like ones placed over their regular voice networks, which under newer smartphone plans typically are subject to no minute or usage limits.
VoLTE represents a fundamental change in the way the carriers handle traditional voice calls. In the past, traditional cellular voice calls essentially got their own separate channel on carriers networks that was completely separate from the data channel. With VoLTE, both voice and data will intermingle in a single data channel.
That change should allow carriers to better divvy up the available bandwidth at each cell tower, since they can repurpose the bandwidth that would have been reserved only for voice calls for data transmissions. That should provide consumers with faster Internet surfing and data access when they are crowded areas with lots of people connected to the same tower.
But the format has some other advantages. Verizon and Sprint s older networks didn t support simultaneous voice and data transmissions from the same radio; with VoLTE, they ll be able to. That means that Verizon iPhone users who are on the road will finally be able to check their email while talking on the phone — at least if they have the new iPhone 6 and they are on a VoLTE call.
It also means that newer Android phones for those networks should have longer battery lives. In order to get around the limitation on talking and surfing, many Android phones for Sprint and Verizon included a second cellular antenna, which tended to drain their batteries more quickly.
Additionally, the carriers are using VoLTE to roll out support for high definition voice calls, which promise to be clearer and sharper than traditional ones.
The new iPhones aren t the only devices that support VoLTE. On Verizon, Samsung s Galaxy S5 and LG s G3 also support the new calling standard. T-Mobile users can choose from among a handful of phone models, including the Samsung Galaxy Light and the Samsung Galaxy Note 3.
Photo: Apple CEO Tim Cook introducing the new iPhone 6 models earlier this month (Karl Mondon/Bay Area News Group).
