VoLTE is short for "voice-over-LTE," which means making and receiving calls using the 4G LTE data network rather than the traditional cellular voice connection. VoLTE is a big thing in telecommunication circles at the moment because LTE does not natively support voice calls. It's a data-only network; this is one of the reasons why LTE is a simpler network to set up for the carriers and why it has significantly higher capacity, faster transmission speeds and reduced latency. VoLTE systems convert the voice call into data, which is then sent along your data connection. For the purposes of this article, let's suppose that the data is decoded at the other handset but this is not always the case; networks have a complicated system to ensure that your call is routed and converted to wherever it needs to. Carriers – and you – should be interested in VoLTE for three reasons and the first is that your handset does not easily and seamlessly move to LTE from other networks. If you are browsing a website using LTE and a traditional voice call comes in, your device will drop to a 2G or 3G network to handle the call. Once the call has concluded, your handset will only upgrade to 4G LTE when the connection is idle. Different network operators and devices handle this in different ways, with some making you wait until you've finished your session, some use the handover from cell to cell and others giving you the inelegant solution of breaking the connection for you and making you wait. You probably switched to a LTE device because you didn't want to wait, right? The other reason why VoLTE is a big thing is that voice converted to data is an efficient use of bandwidth resource. And finally, VoLTE can take advantage of the higher network speeds to enhance the audio quality beyond conventional means.
AT&T have said at the CTIA event, Las Vegas, that they are working with several other carriers to bring direct VoLTE calling between their networks. Providing users have the necessary handset (the Samsung Galaxy S5 and the new iPhones have native VoLTE) and the right network connection, this plan will mean that you'll be able to take advantage of clearer calls and not breaking your LTE connection when you use your smartphone to talk with people. AT&T have already launched VoLTE across areas of Illinois, Indiana, Minnesota and Wisconsin and is able to take advantage of their network's ability to downgrade the call from VoLTE to a 2G or 3G network without dropping the connection. This ability will need to be mirrored with other GSM carriers such as T-Mobile USA. Unfortunately, the ability to downgrade the connection in this way isn't available for CDMA-based networks nor may a network upgrade from 2G or 3G to 4G without breaking the connection.
AT&T's Kris Rinna explained that the network is currently undergoing trials with different carriers to bring the service to the market. She cites some of the difficulties are associated with the asymmetrical speeds of LTE networks (download speeds are much higher than upload speeds); VoLTE requires a symmetrical network speed environment. There are also billing and routing issues to be ironed out. In short, there is a lot of interoperational testing that needs to be carried out first, but cross-network VoLTE will be beneficial for the industry. It's good to see the carriers working together rather than fighting.