[Q] GPE 5.0.1 Lollipop: Is it possible to write to /system/media/audio/ringtones? topic

I am trying to copy two of my ringtones into the /system folder of the phone, but the device is not letting me, it keeps failing on the copy command. Anyone know if this is possible?

I am doing the following:

su
mount -o remount,rw /system
cd /storage/ext_sd
cp r1.ogg /system/media/audio/ringtones/

BTW, the filesystem appears to have been re-mounted in read-write mode, because the output of the "mount" command shows /system to be mounted "rw".

I have tried the above commands via an interactive adb shell, as well as through the "terminal emulator" application and I keep getting the same failure.

Thx!