phone vs telephone system

phone and telephone system both are nouns.

Word	Noun	Adjective	Verb	Adverb
phone	Yes	No	Yes	No
telephone system	Yes	No	No	No

phone (noun)	telephone system (noun)
electronic equipment that converts sound into electrical signals that can be transmitted over distances and then converts received signals back into sounds	a communication system that transmits sound between distant points
electro-acoustic transducer for converting electric signals into sounds; it is held over or inserted into the ear
(phonetics) an individual sound unit of speech without concern as to whether or not it is a phoneme of some language

phone (verb)	telephone system (verb)
get or try to get into communication (with someone) by telephone