Custom ringtone for calls with High Sierra from iphone

[ausparkapp]

I have in the desire to change my ringtone when receiving a phone call with 'Continuity' between my Mac and iPhone.
I have looked into previous posts to this forum and many others over the net, but alas I can't copy my custom ringtone into the Ringtones folder as the OS blocks me from drag-n-dropping it in there.
Is there some way that I can use Terminal or other means to circumvent the OS from blocking me from using a custom ringtone for receiving phone calls on my Mac?

 

[ISKOTB]

off this link....https://goo.gl/ANFPHB

I managed to locate the directory where facetime stores the ringtones
/System/Library/PrivateFrameworks/ToneLibrary.framework/Versions/A/Resources/Ringtones/I tried to add a custom m4r file into that directory however facetime does not recognized it.
The only way I can get it to work for now is renaming 1 of the existing ringtone to Beacon.m4r -> Beacon-backup.m4r then rename my custom ringtone to Beacon.m4r.

Facetime plays the custom ringtone thinking it's one of the default ringtone file.

 

[ausparkapp]

But how do you get the custom m4r file into that directory, drag and drop attempt into there is accompanied with a grey circle with a slash through it (/), I can't even screen shot it.
How do you circumvent these OS restrictions?
I am sure once the file is in the directory, it will play.

 

[ISKOTB]

disable SIP and try again

 

[ausparkapp]

This worked, thank you.