hold the line vs telephone

hold the line is not a noun while telephone is a noun.

Word	Noun	Adjective	Verb	Adverb
hold the line	No	No	Yes	No
telephone	Yes	No	Yes	No

hold the line (noun)	telephone (noun)
	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

hold the line (verb)	telephone (verb)
hold the phone line open	get or try to get into communication (with someone) by telephone
hold the line on prices; keep the price of something constant