International Hydrographic Organization
The IHO was established in 1921 as the International Hydrographic Bureau (IHB). The present name was adopted in 1970 as part of a new international Convention on the IHO adopted by the then member nations. The former name International Hydrographic Bureau was retained to describe the IHO secretariat until 8 November 2016, when a revision to the Convention on the IHO entered into force. Thereafter the IHB became known as the "IHO Secretariat", comprising an elected Secretary-General and two supporting Directors, together with a small staff of 17, at the Organization's headquarters in Monaco.
International Telecommunications Satellite Organization
The headquarters of this organization is located in Washington D.C., United States.
As of June 2013, there are 149 states that are members of ITSO. States join ITSO by ratifying a multilateral treaty known as the Agreement relating to the International Telecommunications Satellite Organization. 
Bulgaria ratified the treaty in 1996 but denounced it and withdrew from the organization in 2012.