Free How Was I Supposed To Know? ringtone for your phone. Listen first, then download the version you like. Original song by Xania Monet. There are 5 versions, from 13 to 89 seconds long. If you like pop, r&b and upbeat ringtones, see the tags below. For iPhone or iPad download the .M4R file. For Android and other phones download the .MP3 file. All ringtones by Xania Monet are collected on the artist page.