This report explores principles that could form the basis for good practices in the establishment of international mobile roaming (IMR) agreements between two or more countries. Given the cross country nature of IMR services and, especially, the fact that wholesale prices are determined by foreign operators outside the jurisdiction of domestic regulators, international co-operation is vital to address the challenges in roaming markets. There is a growing number of IMR agreements, usually reflecting the most travelled international routes, such as in the European Union, the Gulf Cooperation Council in the Persian Gulf Region, Russia with Poland and with Finland, and the countries of the Association of South East Asian Nations (ASEAN). In addition, there are ongoing discussions between Australia and New Zealand and in the South African and South American regions.