Of course after I post that above, I found an open source database of cell phone towers that includes tower IDs. I've been wrestling with it all day and I just now found something that may or may not fit.
At 44.138990 -87.772860 there is an AT&T tower with the Cell ID of 51109 and the LAC of 30996. Cingular bought AT&T a while back so their towers would theoretically be one and the same.
The reason this may be significant is that Teresa had tower pings from a cell ID of 21101/21103 with a L Cell (which I think may be the same as LAC) of 54096. Remember that because of how the cell signal is split, the last number just indicates which direction the signal came from.
(Note that I have read the numbering actually starts with 1 being north/northeast, 2 being southeast/southwest, and 3 being southwest/north.)
So the main number I think we would look at would be the 2110. But all the cell ID numbers on her bill start with a '2' - maybe the 2 isn't significant, either? The 110 in the middle of the tower on her bill corresponds with the 110 on the tower I found. And the '96' is the same on the end of both the L numbers.
Why this is interesting to me is, if she were unable to find the Zipperers or decided to push them off and go to the Averys, at the 1:52 call she could be west of that tower (sector 3, 21103). She'd do her thing at the Averys, then head back south towards the Zipperers by 2:41 (sector 1, 21101).
https://www.google.com/maps/d/u/0/viewer?mid=zli3YMCmyfkI.k2KjexuGbDPY
There's a theory that the Zipperers had a vicious dog, and a lot of stuff about their stories not adding up, hostility during questioning, a weird call-in from an officer about needing animal control and finding a burn pile that had an entire bracelet in it... things that make you go hmm. There are theories about every single person involved in this case. There will probably be a theory about me before the night is out.
On the other hand, it's ENTIRELY possible that I am totally stretching and trying to make this very scant data fit a "pet" theory. But I'm going to see if I can find a X192X tower somewhere around Avery Salvage.
You can, too.
http://opencellid.org