To record calls on Your phone Follow the steps below:
1. Download the ACR call recording app from the play store
2. Then Follow the instructions from the app and allow all the access to the app as shown in the Image below
3. Ten Tap the three bar on the top left of the app.
4. 5. There you will find the Enable option on the top.
6. Enable it and enjoy the app.
You can check the complete specs of this phone: Oppo F9 Pro
You can also check this video for more detailed information
Oppo F9 Pro has got a really string configuration with 2 GHz Octa-Core MediaTek Helio P60 processor bundled with 6 GB RAM. The device runs very smoothly and there are no lagging issues.
However, if there is some issue. The following guide by Oppo itself can help you troubleshoot it.
If your phone is lagging, doesn't run smoothly or has a delayed reaction
If the issue still persists you must visit service center. You can find one from here: Oppo Service Center
You can see detailed specs here: Oppo F9 Pro
Yes, Oppo F9 Pro has a portrait mode as it has dual rear camera (16MP+2MP) . You can see yourself in the UI screenshot of Camera app of Oppo F9 Pro :
To see the complete specifications of this device: Oppo F9 Pro