In the period from circa 1977-1985, candidates who successfully passed an FCC amateur radio examination would be able to operate with their new (upgraded) privileges by appending "/" followed by the two-letter abbreviation of the FCC Field Office or Resident Agent Office iin which they took the exam. On phone, they would typically sign "W1XYZ temporary BS" or "WA3XYZ interim PA". This was necessary until the printed licence was received in the mailed. The FCC offices and their codes are listed below. There may be some omissions from this list. Additional information please to Alan, 5B4AHJ, email address on QRZ.COM.
| FCC Office | Suffix | Mapped by |
| Anchorage AK | AR | Exception |
| Atlanta GA | AT | Exception |
| Baltimore MD | BM | Exception |
| Boston MA | BS | Exception |
Buffalo NY |
BF | No QSOs |
| Chicago IL | CG | Exception |
| Columbia MD | WN | Prefix |
| Dallas TX | DL | Exception |
| Denver CO | DV | Exception |
| Detroit MI | DT | Exception |
| Honolulu HI | HL | Exception |
| Houston TX | HU | Exception |
| Kansas City MO | KC | Prefix |
| Long Beach CA | LB | Exceptions |
| Miami FL | Info wanted | |
Minneapolis–Saint Paul MN |
PL | Exception |
| New Orleans LA | Info wanted | |
| New York NY | NY | Prefix |
| Norfolk VA | NF | Prefix |
| Orlando FL | OR | Exception |
| Philadelphia PA | PA | Exception |
| Portland OR | PO | Exception |
| San Diego CA | SD | Exception |
| San Francisco CA | SF | Exception |
| San Juan PR | SJ | Exception |
| Savannah GA | SV | Exception |
| Seattle WA | ST | Exception |
| Tampa FL | TP | Exception |
More recently, those who have requested a licence modification (class upgrade) must add "/" followed by a two-letter sufex per the following table:
| Licence class upgrade | Suffix | Mapped by |
| Novice to General | KT | Prefix |
| Novice or Technician to General | AG | Prefix |
Novice, Technician, General or Advanced to Amateur Extra |
AE | Prefix |
Acknowledgements
Jim Reisert, AD1C
References
May 1994 QST published by ARRL, pp 54-59 An Overview of Amateur Callsigns - Past and Present
FCC EB - Regional & Field Offices
Wikipedia Amateur Radio Licensing in the United States