Mobile devices, by default do NOT have the same fonts/typeface that are installed on a desktop system such as Windows or Mac OS. While some users may have installed additional fonts/typeface onto their device, the out of the box options often do not include several of the standard web fonts/typeface that Claro supports. In these cases an alternate font/typeface will be substituted.
See iOS 7 Font List and Android Typography for more information.
Below are some images of Claro's supported fonts, along with screenshots of how those same fonts appear on both an iOS device and an Android device.
Supported Fonts As They Appear in Claro
Claro's Supported Fonts on an iOS Device
Claro's Support Fonts on an Android Device