The interchange qualifier is used to describe the interchange identifier. For example, if we have a qualifier 12, it says that the interchange identifier is a phone number. Here's the list of all the valid identifiers in EDI (X12 - V004010)
01 - Duns (Dun & Bradstreet)
02 - SCAC (Standard Carrier Alpha Code)
03 - FMC (Federal Maritime Commission)
04 - IATA (International Air Transport Association)
08 - UCC EDI Communications ID (Comm ID)
09 - X.121 (CCITT)
10 - Department of Defense (DoD) Activity Address Code
11 - DEA (Drug Enforcement Administration)
12 - Phone (Telephone Companies)
13 - UCS Code (The UCS Code is a Code Used for UCS Transmissions; it includes the Area
Code and Telephone Number of a Modem; it Does Not Include Punctuation, Blanks or Access Code)
14 - Duns Plus Suffix
15 - Petroleum Accountants Society of Canada Company Code
16 - Duns Number With 4-Character Suffix
17 - American Bankers Association (ABA) Transit Routing Number (Including Check Digit, 9 Digit)
18 - Association of American Railroads (AAR) Standard Distribution Code
19 - EDI Council of Australia (EDICA) Communications ID Number (COMM ID)
20 - Health Industry Number (HIN)
21 - Integrated Postsecondary Education Data System, or (IPEDS)
22 - Federal Interagency Commission on Education, or FICE
23 - National Center for Education Statistics Common Core of Data 12-Digit Number for Pre-
K-Grade 12 Institutes, or NCES
24 - The College Board's Admission Testing Program 4- Digit Code of Postsecondary Institutes, or ATP
25 - American College Testing Program 4-Digit Code of Postsecondary Institutions, or ACT
26 - Statistics of Canada List of Postsecondary Institutions
27 - Carrier Identification Number as assigned by Health Care Financing Administration (HCFA)
28 - Fiscal Intermediary Identification Number as assigned by Health Care Financing Administration (HCFA)
29 - Medicare Provider and Supplier Identification Number as assigned by Health Care Financing Administration (HCFA)
30 - U.S. Federal Tax Identification Number
31 Jurisdiction Identification Number Plus 4 as assigned by the International Association of Industrial Accident Boards and Commissions (IAIABC)
32 - U.S. Federal Employer Identification Number (FEIN) 33 National Association of Insurance Commissioners Company Code (NAIC)
34 - Medicaid Provider and Supplier Identification Number as assigned by individual State Medicaid Agencies in conjunction with Health Care Financing Administration (HCFA)
35 - Statistics Canada Canadian College Student Information System Institution Codes
36 - Statistics Canada University Student Information System Institution Codes
37 - Society of Property Information Compilers and Analysts
AM - Association Mexicana del Codigo de Producto (AMECOP) Communication ID
NR - National Retail Merchants Association (NRMA) - Assigned
SN - Standard Address Number
ZZ - Mutually Defined