At the moment, all voice calls on Verizon's network requires the phone to connect over Verizon's old 3G CDMA network - not over Verizon's newer 4G/LTE network.
This is why some phones (including all iPhones) can not support simultaneous voice calls and data connections on Verizon's network, and why occasionally an area with seemingly great data coverage has no voice support, or vice-versa. For Verizon, the underlying voice and LTE data networks are based upon completely different technologies.
Verizon is eager to start phasing out (and eventually shutting down) its 3G network, and to reduce reliance on it Verizon has long been planning to move to supporting voice calls over its LTE network, a technology known as VoLTE (aka "Voice Over LTE").
Verizon has been talking about VoLTE since 2010 - initially promising deployment by 2012, and in May 2014 announcing VoLTE "by the end of this year".
Today Verizon at last got a slight bit more specific - announcing the marketing name for VoLTE service as "Advanced Calling 1.0", and revealing "HD Voice" and "Video Calling" as the two key features that will make enabling VoLTE appealing to users.
But Verizon didn't get too specific just yet - the actual go-live date was left a vague "in the coming weeks", and Verizon even refused to disclose which current phone models will receive software upgrades to support "Advanced Calling".
Here is what we do know:
- HD Voice: VoLTE enables higher data rates for voice calls, and more processing power for background noise cancellation. Verizon claims that "HD Voice sounds as if the person you're calling is standing right next to you."
- Video Calling: Since voice calls are just bits on the LTE data network, Verizon will be able to offer seamless transitions between voice and video calls without needing a separate video chat app like Skype involved. The overall experience sounds very similar to Apple's FaceTime - with video calls dialed by phone number or directly from your address book.
- Connection Compatibility: Though eventually VoLTE will be a worldwide standard, at the moment there is no attempt at cross-carrier compatibility. To take advantage of HD Voice and Verizon Video Calling, both parties must have Advanced Calling 1.0 compatible devices on Verizon's LTE network.
- Billing: Verizon has confirmed that HD Voice calls will be treated no differently than regular voice calls, and the data used will not count against your data allotment and instead will count as "minutes" - and most Verizon plans now include unlimited voice minutes. Video calls on the other hand DO count against your data allotment, and can burn up to 8MB per minute -- or 480MB per hour!
- Coverage: Unlike AT&T, which is currently testing VoLTE in just a three cities - when Verizon turns on VoLTE it will be nationwide - everywhere Verizon has LTE service. Verizon has also confirmed that calls will be able to be made over WiFi connections as well, and calls over WiFi will not count against your data allotment.
- Dropped Calls: If you cross into a place where there is no Verizon LTE service however, any HD Voice or video call in progress will drop. Verizon does not have any support for automatically switching back to the old 3G voice network. You'll have to dial again, and connect the low-fi way.
Verizon has refused to confirm which phones will get upgraded to support the new "Advanced Calling 1.0" features, but in demos they have used the Samsung Galaxy S5 and LG G2, so those two are almost certain to be supported. I expect that when iOS 8 and the iPhone 6 launch next month, they will be supported as well - and probably retroactively the iPhone 5S, 5C, and maybe even the iPhone 5.
It is probably safe to assume that current "flagship" phones being sold by Verizon will eventually get support, but odds are that a lot of older phones will not.
VoLTE isn't just for Verizon - though Verizon is the only carrier to announce video calling support coming as a core feature alongside VoLTE's HD Voice capabilities. But all the carriers are eager to embrace HD Voice and to move voice support off of their 3G networks and onto LTE too.
Sprint has announced VoLTE is "coming" but no specific plans (rumors point to mid-2015), AT&T is currently testing VoLTE in three cities with a single supported phone model, and T-Mobile has just turned on nationwide support with 4 supported phone models.
By the end of the year, VoLTE will likely begin to be widely deployed by multiple carriers with a wide range of supported devices - perhaps even Sprint will have announced solid plans by then.
For anyone in the market for a phone - it is smart to make sure that whatever you get will be VoLTE compatible.
Or as Verizon calls it, "Advanced Calling 1.0" compatible.