This are 100% free. You are not going for the paid report, the free is all you need. These will give you a name for a number, and a number for an email… That is a free clue!
FastPeopleSearch.com
Spytox.com
Melissa.com
Mylife.com
FreeCarrierLookup.com
freecarrierlookup.com and some of the other ones above will let you know if the number is a VOIP number like Google Voice, or TextNow and others which of course enables anonymity.