Where is telephone country code 87?

Country codes beginning +87 are global services, not specific to any country.

+870 = Inmarsat, mostly for ship-to-shore calling

+878 = universal personal numbers

+871 through +874 were formerly used for Inmarsat

+875, +876, and +877 are reserved for maritime satellite phone services

+879 is reserved for an unspecified non-commercial service