You cannot make calls or send text messages with the Galaxy Watch4 without a paired mobile, as these functions require a connection to a smartphone. The installation of apps such as Strava is also only possible via the paired smartphone. Without a mobile phone, however, you can use NFC to make payments and display the time. Listening to music is possible if the music is stored on the watch or is played via Bluetooth headphones, provided the watch is connected to a device that plays the music.