Over The Air Bitmap Font (.otb)
The OTB (Over The Air Bitmap) file extension, primarily developed by Nokia, is used for transmitting black-and-white bitmap images between mobile phones, particularly Nokia and Siemens models. These images, limited to 255x255 pixels, are often encoded in hexadecimal or binary format and transmitted via SMS. Historically, OTB files facilitated the exchange of simple graphics in the early mobile communication era, enhancing user experience with visual content. This format, though now largely obsolete, played a crucial role in the evolution of mobile image-sharing technology.