No problem, I hadn't looked too closely but you are right, 0 is valid (and recognized by the app as such) -- internally, I set it to -1 unless a valid value is returned anyway, so that shouldn't be too bad.
Let me know when you get your side ready, no rush. The current alpha build I'm working on is half-broken as I try to implement this new TelephonyCallback stuff I'm working on.
I’d recommend against using 0 because It’s actually possible to assign a TAC of 0 (in LTE the range is 0 to 65535 and in NR the range is 0 to 16777215).
My thought process with -1 was that some sort of error could in theory cause a blank or an empty value to end up in an upload file. A -1 feels a bit more intentional.
I’ll see if I can get the backend up and ready to go this weekend (hopefully before the app update is released).
Added, and 2 more estimated sites:
T-Mobile eNB 876480. Looks like its located at (40.62210996397784, -73.97627312607108), as the tower looks like a Sprint setup.
T-Mobile eNB 875632. Both this site and Sprint eNB 9022 seem to be located at (40.61640722407462, -73.96985178560767).