get together vs call in

get together is a noun but call in is not a noun.

Word	Noun	Adjective	Verb	Adverb
get together	Yes	No	Yes	No
call in	No	No	Yes	No

As verbs, call in is a hyponym of get together; that is, call in is a word with a more specific, narrower meaning than get together:

Other hyponyms of get together include pick up, reunite, rendezvous, call, visit, celebrate, fete.

get together (noun)	call in (noun)
a small informal social gathering

get together (verb)	call in (verb)
get together socially or for a specific purpose	make a phone call
become part of; become a member of a group or organization	summon to a particular activity or employment
get people together	summon to enter
	cause to be returned
	demand payment of (a loan)
	pay a brief visit
	take a player out of a game in order to exchange for another player