phone system vs telephone

phone system and telephone both are nouns.

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

phone system (noun)	telephone (noun)
a communication system that transmits sound between distant points	electronic equipment that converts sound into electrical signals that can be transmitted over distances and then converts received signals back into sounds
	transmitting speech at a distance

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