We humans aren’t so special:
The evidence that dolphins use signature whistles like names has been building since they were first discovered in the 1960s. They can convey a dolphin’s identity, as well as its mood and motivation. Individuals invent their own whistles at a few months of age, possibly with some influence from their mums. They’ll keep the same call for decades, although males sometimes change theirs to resemble the whistle of a new ally.
The whistles are clearly important, since they account for half of all the calls that wild dolphins make. They can mimic each other’s signatures, but they usually call with their own, perhaps to broadcast their identity and keeping in touch while swimming.