In our app we are using Android’s intent mechanism with ACTION_DIAL. All working properly when there is no plus sign in the number. With plus sign it works well on all Android devices besides Samsung. It happens to a client with A51 device and some more Samsung devices. On Stackoverflow someone posted the exact same issue https://stackoverflow.com/q/66315211/1020530.
Based on the RFC using phone numbers with their Global number format (using the plus sign and country code) is recommended.
It does work well on the same device when using a link with the tel URI from the browser including the plus sign.
The user is using Samsung stock dialer app.