call in vs drop in

call in and drop in both are verbs.

Word	Noun	Adjective	Verb	Adverb
call in	No	No	Yes	No
drop in	No	No	Yes	No

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

Other hyponyms of call in include see, see, come by, drop by, call on.

call in (verb)	drop in (verb)
make a phone call	visit informally and spontaneously
summon to a particular activity or employment
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