phone number vs telephone number

phone number and telephone number both are nouns.

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

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

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

Other synonyms of phone number include number.

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