There is only one file type that uses the .WBMP extension:
Wireless Bitmap Image File
Black and white bitmap image format used by mobile devices such as cell phones and PDAs; can be sent from one phone to another via the SMS messaging protocol; similar to a standard bitmap (.BMP) file, but only supports monochrome (1-bit) image data.
As mobile phones have become more advanced, the WBMP format has largely been replaced by full color image and video formats.
Updated: February 16, 2019