LTE (Long-Term Evolution) — often marketed as 4G LTE — is a wireless high-speed data transmission standard for mobile phones and other data-enabled terminals. It is based on GSM/EDGE and UMTS/HSPA network technologies, increasing throughput and speed by using a different radio interface along with improvements to the core network. The standard was developed by 3GPP, a consortium responsible for creating specifications for mobile communications.
Although mobile operators and device manufacturers often label LTE networks as
Theoretically, LTE can deliver speeds of up to 326 Mbit/s, while real-world mobile Internet speeds can reach around 100 Mbit/s. Actual speeds depend heavily on signal quality and base station load, meaning the average speed is typically several times lower.
LTE is a natural upgrade for both GSM/UMTS and CDMA2000 network operators. Different countries use different frequency bands for LTE, so only multi-band phones can connect to LTE networks worldwide.
A key technological limitation of LTE is its inability to handle voice calls natively. The first solution to this issue was CSFB (Circuit Switched FallBack), which, during an outgoing or incoming call, switches the subscriber back to earlier-generation networks — GSM or UMTS. This is the most common method for voice calls in LTE networks in Russia, but it causes delays in call setup between subscribers.
Another approach to voice transmission in LTE networks is VoLTE, which sends voice as IP packets without switching to earlier-generation networks. However, VoLTE must be supported by both the mobile operator and the device. Most popular mid-range and flagship smartphones now support VoLTE. In Russia, VoLTE is used to a limited extent by all major operators of the "big three."