Under IOS the Owler interface for the Foscam FI9828p camera offers buttons for push to Talk, mute sound and toggle IR mode.
For newly added FI9900 cams only push to talk is visible.
This is completely separate from the the PTZ interface on/off setting.

I noticed that When I changed my FI9828 cam in the network for a FI9900 with keeping the same settings for Owler, all interface functions stayed available and everything was funtioning well with the FI9900 cam.