The company OnePlus should finally take care of the full support of VoLTE and WiFiCall at the three major German providers (Telekom, Vodafone, o2). So far even the flagships do not support any of these technologies, although on the hardware side all prerequisites exist and the technology is also advertised in Germany in the hardware specifications.
OnePlus has developed the OnePlus 6, a very competitive product that does not support the simplest communication technologies, at least in Germany.
These would be VoLTE and WiFiCall. In India, these technologies are supported. In Germany, with identical hardware, but not. This is due to the reluctance of Oneplus to implement the techniques correctly and completely.
Important are the mentioned technologies for users with little to no reception in the 2G and / or 3G network. Telephone calls could be transmitted over the LTE network, or WLAN. However, this is not possible because of OnePlus itself.
Inquiries concerning this problem are answered via ChatBot, with the immediate answer that there is no agreement with e.g. the telecom would exist.