phone has 10 distinct synonyms spread across 4 of its 4 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
electronic equipment that converts sound into electrical signals that can be transmitted over distances and then converts received signals back into sounds
“I talked to him on the telephone”
(phonetics) an individual sound unit of speech without concern as to whether or not it is a phoneme of some language
electro-acoustic transducer for converting electric signals into sounds; it is held over or inserted into the ear
“it was not the typing but the earphones that she disliked”
get or try to get into communication (with someone) by telephone
“I tried to call you all night”
Synonyms, antonyms and the broader and narrower relations for phone come from Princeton University’s WordNet. Full sources and licences.