I believe I know the meaning of the "CNA" and the "ours 303-293-2333" notations on the scratch paper from Jane Doe's lockbox. I think the fraud lawyer and oil company identifications previously mentioned are most likely red herrings.
I searched Google Books for the string 303-293-2333. On my computer, the second result was snippet views from the following book:
How to find missing persons: a handbook for investigators/ Ronald George Eriksen 2 [sic] (Loompanics; Port Townsend, Washington, 1984), pages 83 and 84.
This book exists in at least three versions: a staple-bound "true first edition" published by Loompanics in 1981 in their original Mason, Michigan location; the 1984 edition I refer to above; and a 1994 2nd edition, revised and expanded.
I was able to get my hands on the 1994 edition, but had to request a scan of the relevant Chapter 19 (Telephone Records) of the 1984 edition from a public library. Luckily, they came through quickly. See the attached two-page PDF (handwritten notes are mine).
The author explains "[f]ortunately, Ma Bell has secret telephone numbers called "C.N.A. Service numbers" which you call, give the number in question, and you will be told the name and usually the address which correspond with that number." He further explains that the numbers are changed "at regular intervals" and that the information he gives is good "as of the first of 1984."
Following is a table of area codes, with the corresponding C.N.A. numbers. The number 303-293-2333 matches seven area codes (note that Google Books only indexes two of them). According to Wikipedia, all seven were in the batch of original area codes instituted in 1947, and most served the entire referenced state until the 1990s or 2000s.
505 New Mexico
My interpretation of Jane Doe's notes is that "ours" refers to her own area code sometime in the 1980s, possibly prior to her name changes. I lean toward Idaho or Arizona due to other elements in the story, but of course, I'm not sure.
Just to be clear, I am also not sure at all that Jane Doe used this particular book as a reference. I do think, however, that her notes almost certainly refer to the Customer Name and Address Service.