From Navy Times: “Some are part of the U.S.-fostered Combined Task Force 151, led at the moment by a Turkish admiral.
Other combatants in the area fall under a NATO mission called Operation Allied Protector, ships that include the U.S. frigate Halyburton, led from the flagship frigate Côrte Real of Portugal.
The European Union organized its first maritime task force for the counterpiracy mission, known as EU NAVFOR-Atalanta, which in addition to German, Greek, Spanish and French ships boasts a newcomer to such warm waters — two corvettes and a supply ship from Sweden. And finally there are the independent operators such as China and Russia who arrived with various mandates, to include protecting their nation’s commercial shipping.
On top of that, perennial foes India and Pakistan are onboard, along with two ships from the Iranian navy — the frigate Alborz and fleet supply ship Bushehr . . .

To prevent such potential dust-ups, allied nations use established systems to communicate, while there have also been some work-arounds to handle newcomers — China, for example.
‘We just e-mail communications with the Chinese navy’s Yahoo account,’ said Cmdr. Jane Campbell, a spokeswoman at 5th Fleet in Bahrain.”