telco vs phone company

telco and phone company both are nouns.

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

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

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

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

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