Mobile Phone Technology

VoLTE (Voice over LTE) is the protocol used to make phone calls via the 4G network.

2G networks were primarily designed for phone calls, with data services added on top. When making a phone call, the connection switches to the PSTN (public switched telephone network).

4G (and subsequently 5G) is an IP-only network and will deliver phone calls over the data network using VoLTE. There is no switching between data and voice within the network; everything is data. VoLTE is designed for the LTE network and makes efficient use of it. If necessary, VoLTE can switch to VoWiFi to keep the call alive, and vice versa.

In the early days of 4G, VoLTE was not available everywhere, so phones would switch back to 2G. This resulted in comments such as 'I cannot make phone calls', which were due to a lack of suitable 2G coverage. The same fallback works today if necessary. Also, if a 4G phone calls a 2G phone, the call reverts to the 2G network. Call quality over 4G (VoLTE) is noticeably better than over the 2G network. This is primarily because the input sound wave is sampled at twice the rate of the sampling in 2G.

Another advantage of VoLTE for heavy mobile users is that data can be uploaded/downloaded in parallel with the phone call, making the network very efficient for users.

Video calls are also possible with VoLTE.

VoLTE is not the same as VoIP. VoIP is a more general protocol used by landlines to access the data network rather than a dedicated phone network.

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