The Simple English Wikipedia has an article on:

Smartphone

Pronunciation [ change ]

• ( UK ) IPA ^{( key )} : /?sm?ːtf??n/
• ( US ) IPA ^{( key )} : /?sm?rtfo?n/

• Audio (US)

  ( file )

Noun [ change ]

1. ( countable ) A smartphone is a mobile personal computer with a mobile operating system with features useful for mobile or handheld use.