ITU prefix/Grid chart

Linked country codes are from ISO 3166-1.

Series allocated to an international organization.
Provisional allocation in accordance with No. S19.33: "Between radiocommunication conferences, the Secretary-General is authorized to deal with questions relating to changes in the allocation of series of call signs, on a provisional basis, and subject to confirmation by the following conference."
Half series allocation. The first country listed uses all callsigns beginning with the listed prefix followed by A-M, and the second country listed uses N-Z.