armed forces vs call up

armed forces and call up both are nouns.

Word	Noun	Adjective	Verb	Adverb
armed forces	Yes	No	No	No
call up	Yes	No	Yes	No

armed forces (noun)	call up (noun)
the military forces of a nation	an order to report for military duty

armed forces (verb)	call up (verb)
	recall knowledge from memory; have a recollection
	get or try to get into communication (with someone) by telephone
	bring forward for consideration
	call to arms; of military personnel
	cause to become available for use, either literally or figuratively