call in vs call on

call in and call on both are verbs.

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

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

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

call in (verb)	call on (verb)
make a phone call	have recourse to or make an appeal or request for help or information to
summon to a particular activity or employment	to visit someone, usually for a short time
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