telephone call vs telephony

telephone call and telephony both are nouns.

Word	Noun	Adjective	Verb	Adverb
telephone call	Yes	No	No	No
telephony	Yes	No	No	No

As nouns, telephony is a hypernym of telephone call; that is, telephony is a word with a broader meaning than telephone call:

Other hypernyms of telephone call include telephone.

telephone call (noun)	telephony (noun)
a method of contacting a person by phone	transmitting speech at a distance