With Filestar you get 18 different skills for working productively with AT&T Group 4 (.att) files.
About .Att
Name
AT&T Group 4
Extension
.att
Format
Binary
Category
Raster Image
Developer
AT&T Laboratories Cambridge
Description
AT&T Group 4 is a file format used for compressing high-resolution data. It is most commonly used for storing images such as TIFFs, JPEGs, and GIFs. The format is lossless, meaning that no data is lost during compression.