OnePlus
Change Default Dialer App auf OnePlus
OnePlus lets you assign any installed calling app as the handler for outgoing calls, contact search and the incoming call screen. This matters if a third-party dialer offers better spam detection, a cleaner call log or reverse number lookup that the stock app lacks.
Android only shows one active default at a time. If you install a new dialer app but calls still open in the old interface, the system has not switched the assignment yet - it does not happen automatically for every app.
To set a new default, go to Open the Settings ➔ Tap on Apps & notifications ➔ Tap on Default apps ➔ Tap on Phone app ➔ Choose the default Phone app. Only apps built to handle calls appear in that list.
Switching the default dialer can reset call-related permissions such as contact access or call log access for the newly chosen app. Grant those permissions again if calls fail to connect or contacts do not show up.
If the new app still does not receive calls after this change, check whether it is also excluded from battery optimization, since background restrictions can block incoming call notifications independently of the default dialer setting.