phone company vs telephone company

phone company and telephone company both are nouns.

Word	Noun	Adjective	Verb	Adverb
phone company	Yes	No	No	No
telephone company	Yes	No	No	No

As nouns, phone company and telephone company are synonyms defined as:

phone company and telephone company: a public utility that provides telephone service

Other synonyms of phone company include phone service, telco, telephone service.

phone company (noun)	telephone company (noun)
a public utility that provides telephone service	a public utility that provides telephone service