O2 Czech Republic has launched VoLTE commercially, with customers initially offered the service on Samsung devices.
The service is available on the Galaxy S7 and S7 Edge, with other smartphones supporting VoLTE to be announced in February and March, the operator said.
O2 partnered with Nokia to launch the service.
The Galaxy S7 and S7 Edge will both be discounted by CZK5000 (around €185) as part of the promotion, with the S7 available for CZK14,745 (around €545) and the S7 Edge for CZK17,595 (around €651).
O2 is the last operator to launch VoLTE in the Czech Republic. It claims that its 4G network is now available to 99 percent of the population.
T-Mobile launched the service commercially in 2015 after running trials in 2014, working with several manufacturers.
In 2016, Vodafone Czech Republic launched VoLTE and Wi-Fi calling after getting Ericsson to enable its network.
According to a report published by Ovum, operators are turning to VoLTE to cut costs and use spectrum more efficiently.
The report said that VoLTE connections will rise from 324 million in 2017 to hit 3.33 billion by 2021, reaching 53 percent of total cellular global subscriptions. Currently most connections are carried over 3G and 2G.