It is possible that few devices display a wrong or not updated mobile network signal strength. In this case the signal strength measurement is not shown by the App, and respectively discarded.
Under the operating system iOS (iPhone, iPad) and in the web browser app, the signal strength is not available.
RUNDFUNK UND TELEKOM
REGULIERUNGS-GMBH
Austrian Regulatory Authority for Broadcasting and Telecommunications
Mariahilfer Straße 77-79, 1060 Vienna, Austria
tel.: +43 1 58058-0