If the person sent, for example, a pornographic image or an image that is indecent or prohibited from being sent, it seems obvious to me. You've moved on to the next step if you find a phone number associated with an image of a pornographic scene. You truly have reasonable grounds to believe that an offence has been committed. With this kind of photo, we can all agree that you're no longer just suspecting. It's clear that there is trafficking in or use of pornographic or child pornography images.
When you have this image, it seems to me that you've reached your threshold—that you have reasonable grounds to believe.
Isn't that right?