telephone number vs phone number

telephone number and phone number both are nouns.

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

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

telephone number and phone number: the number is used in calling a particular telephone

Other synonyms of telephone number include number.

telephone number (noun)	phone number (noun)
the number is used in calling a particular telephone	the number is used in calling a particular telephone