If I am so allowed to mention this I am.
I am not going to put up a link to the post unless a mod allows it..there is a large post on this on mygmrs forums. Plus I think you'd need a login there to see it. Not sure.
It is a repeater ID'ing "015" DTMF. It appears to be coming from lower Manhattan NYC.
Me and some MyGMRS community members are working to figure this mystery out.