Mobile message type specification - OTA bitmap SMS
(SMS message type, SMS message format)

Introduction

An OTA bitmap is used for various SMS formats: Operator logo, CLI icon, Picture Message, and Downloadable Profile. In most phones the maximum size of the operator logo and the CLI icon is 72 x 14 pixels, while the maximum size of the picture message and the screen saver is 72 x 28 pixels. An OTA bitmap consists of a bitmap header and bitmap data. The size of the bitmap is specified in the header.

A typical OTA bitmap (72 x 14 pixels) header is: 00480E01

The image data is located after the header information and is encoded as follows. Each semi-octet in the OTA bitmap presents 4 pixels in the original bitmap. As one row takes 18 semi-octets, the whole 72 x 14 (operator logo and CLI icon) bitmap takes 18 x 14 = 252 semi-octets = 126 octets. Including the picture message and the screen saver, the entire 72 x 28 size bitmap takes 18 x 28 = 504 semi-octets = 252 octets. For example, if the first four pixels of the image are 1010 (1 - black, 0 - white), the first semi-octet of the OTA bitmap data is hex A.

Here is an example of a simple OTA bitmap (72 x 14 pixels). In the picture, there are two black lines and several black dots: