Telefónica Deutschland has started a project to roll out voice over LTE and voice over Wi-Fi to its customer base.
The two services will be available to both contract and prepaid customers with compatible handsets.
The operator, which has 48.4 million customers, said it is working on a "gradual" implementation of the services and should have the project completed by the end of March 2018.
Telefónica Deutschland claimed both services would offer high definition voice and "significantly" shorter call set-up times.
Cayetano Carbajo Martín, Chief Technology Officer of Telefónica Deutschland, said: “We set new standards for our customers’ mobile freedom. This is why, as the first network operator in Germany, we will offer WiFi calls and voice over LTE via our high-performance LTE network for all our customers.
“We want to offer our customers an optimal user experience in the mobile network of Telefónica Deutschland. This is why we work consistently to further optimise our voice and data services.”
According to figures from the GSMA, there are 1,114 devices compatible with voice over LTE. To date, 125 operators have launched the service across 63 markets.
Ericsson predicted last year that there would be 540 million subscriptions by the end of 2017, increasing to 4.6 billion by the end of 2022.
However, it noted that adoption in Europe was behind that of the rest of the world. It said: "In Europe, the service is used by fewer people, as many launched networks still require subscribers to configure VoLTE themselves in the device settings, or to buy a special VoLTE subscription. Past launches of the service demonstrate that for VoLTE usage to take off, automatic operator provisioning is necessary."
It did not give corresponding figures for VoWiFi.