OTB to FAX Converter

OTB to FAX conversion — modern image format in seconds

Drop files here. 1 GB maximum file size or Sign Up
to
Facebook Amazon Microsoft Tesla Nestle Walmart L'Oreal

Format Upgrade

Move from early Nokia mobile eran OTB to the modern FAX format — enjoy fax transmission image encoding and broad software compatibility.

Browser-Based Tool

No software to download — convert OTB to FAX entirely in your web browser. Works on any device with an internet connection.

Privacy Protected

Your OTB files are deleted immediately after conversion to FAX. Converted files are automatically removed from servers within 24 hours.

How to convert OTB to FAX

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose fax or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your fax file right afterwards

About formats

OTB (Over-the-Air Bitmap) is a monochrome image format developed by Nokia as part of their Smart Messaging specification in 1997, designed for transmitting small graphics — operator logos, group graphics, and picture messages — to Nokia mobile phones via SMS. OTB files contain 1-bit (black and white) images at small fixed resolutions, typically 72x14 pixels for operator logos and 72x28 pixels for group graphics, encoded in a compact binary format suitable for embedding within the payload of SMS text messages. The format uses a simple structure: a header byte indicating whether the image is an operator logo or group graphic, width and height values, and the raw bitmap data where each bit represents one pixel packed eight per byte. The extremely tight format — designed to fit within a single SMS message (140 bytes maximum payload, shared with addressing overhead) — reflects the severe constraints of mobile communication in the late 1990s. Nokia's Smart Messaging system was one of the first commercial implementations of rich content delivery to mobile phones, and OTB images represented the entire visual content capability of Nokia handsets before MMS and mobile data browsing arrived. One advantage is the format's historical role as a pioneer of mobile visual messaging: OTB images were among the first graphics that ordinary consumers could send to each other's phones, predating MMS, camera phones, and smartphones by nearly a decade. The format's minimal footprint is another characteristic — entire images fit in a few dozen bytes, reflecting an era of extreme bandwidth constraints. OTB files are supported by ImageMagick, various Nokia phone management tools, and specialty mobile format utilities.
Developer: Nokia
Initial release: 1997
FAX is a generic image file extension associated with facsimile transmission formats standardized by the ITU-T (formerly CCITT), with the underlying Group 3 compression standard ratified in 1980. FAX files typically contain monochrome (1-bit, black and white) image data compressed using the Modified Huffman (MH) encoding defined in ITU-T Recommendation T.4, which assigns variable-length codes to run lengths of consecutive white or black pixels along each scanline. The standard resolution for Group 3 fax is 204x98 dpi (normal mode) or 204x196 dpi (fine mode), reflecting the capabilities of thermal and laser fax machines of the era. FAX files encountered digitally are often raw Group 3 encoded bitstreams or TIFF wrappers with CCITT Group 3 compression (TIFF compression tag 3). The Group 3 encoding scheme is highly efficient for typical business documents — pages with mostly white space and black text — achieving compression ratios of 10:1 to 20:1 compared to uncompressed bitmaps. One advantage is universal fax system compatibility: Group 3 encoding is the mandatory baseline for all fax machines worldwide, meaning FAX files contain data in exactly the format transmitted over telephone lines, preserving the original fax data without transcoding losses. The format's role in business communications history provides another dimension — billions of fax transmissions using this encoding moved legal documents, medical records, and business correspondence for decades, and archived FAX files represent an important documentary record. FAX images can be viewed and converted using LibreOffice, ImageMagick, GIMP, and standard document management systems.
Developer: ITU-T
Initial release: 1980

Frequently Asked Questions

Why would I convert OTB to FAX?

Few modern tools handle OTB natively. FAX provides fax transmission image encoding, making it widely recognized across operating systems and applications.

What programs open FAX files?

Open FAX using ImageMagick, IrfanView, fax software, GIMP. Cross-platform support means you can access these files on virtually any system.

What platforms support this OTB converter?

The converter works on any platform with a web browser — Windows, macOS, Linux, Android, and iOS all supported for OTB to FAX conversion.

Does converting OTB to FAX affect quality?

The conversion preserves the visual content of your OTB image. FAX will reproduce the same pixel data within the limits of its format capabilities.

Is OTB to FAX conversion free?

You can convert OTB to FAX for free on Convertio. Premium plans are available if you need higher throughput or larger file allowances.

Can I convert multiple OTB files to FAX at once?

Convertio supports batch mode — drag in multiple OTB files and they all convert to FAX together, which is much faster than one-by-one.