"Teléfono de inmigración" is a Spanish phrase that translates into English as "immigration's telephone." The word "de" is dropped in translation, but it means "of" in English. A literal translation is "telephone of immigration."
"Teléfono" is a Spanish masculine noun, and when translated into English it's used to refer to both, the actual telephone apparatus and the telephone number. The word "inmigración", which signifies "immigration," is a noun used to define the movement of people from one country to another to change residence. The word also refers, in both Spanish and English, to the government office that controls migratory movements.