telephoner vs caller

telephoner and caller both are nouns.

Word	Noun	Adjective	Verb	Adverb
telephoner	Yes	No	No	No
caller	Yes	Yes	No	No

As nouns, telephoner and caller are synonyms defined as:

Other synonyms of telephoner include caller-up, phoner.

telephoner (noun)	caller (noun)
the person initiating a telephone call	a social or business visitor
	the person initiating a telephone call
	the person who convenes a meeting
	someone who proclaims or summons in a loud voice
	a person who announces the changes of steps during a dance
	the bettor in a card game who matches the bet and calls for a show of hands
	an investor who buys a call option

telephoner (adjective)	caller (adjective)
	providing coolness
	fresh