phoner vs caller-up

phoner and caller-up both are nouns.

Word	Noun	Adjective	Verb	Adverb
phoner	Yes	No	No	No
caller-up	Yes	No	No	No

As nouns, phoner and caller-up are synonyms defined as:

Other synonyms of phoner include caller, telephoner.

phoner (noun)	caller-up (noun)
the person initiating a telephone call	the person initiating a telephone call