Just a guess, but you get a failed fax notice when a fax does not go through, but it will retry. So of the 31 notifications you got, 28 of them probably ultimately went through. The probable reason you got the failures is from the machine you were sending to being busy at the time of the original submission. You probably just have the 3 that never went through. You can verify these by checking corresponding faxes that did go through with the failures. Those should somewhat match up. I'm not a Tech, so again, just a guess.