A. 1. Check your network settings and ensure you have a stable connection. 2. Go to Settings > Apps > Phone > Storage and clear the cache. 3. Restart your phone to refresh the system.
B. 1. Disable battery optimization for the Phone app by going to Settings > Battery > Battery optimization and selecting the Phone app to not optimize. 2. If the problem continues, consider checking for any pending software updates in Settings > System > System updates.