ESCO (Emergency Service Central Office Number) is the information delivered to the PSAP when there is an ANI failure between the end office and the 9‑1‑1 Control Office. When ANI is not available, the 9‑1‑1 call is default routed and the ANI display at the PSAP will be “911-0TTT” (or 911-TTTT) with TTT identifying the incoming trunk group.
Relevant NENA Documents
Note: To find and download the document, copy the document number (like NENA-STA-010) from below and search the NENA Standards and Documents page.
NENA 08-502, NENA Generic E9-1-1 Requirements Technical Information Document (TID)