"Numeros de telefono" is Spanish for "telephone numbers." The expression consists of two nouns, "numeros" and "telefono" and a preposition, "de."
The expression "numeros de telefono" is a plural one. The singular version would be "numero de telefono." The noun "numeros" also translates in English as figures, issues, numerals, performances and sizes. When used in reference to phones, however, it means "numbers." The Spanish expression for making a phone call is "llamar por telefono." To let someone know that a person is talking on the phone, one would say "esta hablando por telefono" in Spanish. This expression is used for both masculine and feminine subjects.