With bandwidth so low for most wireless devices, it is very important to reduce the size of individual files so that a user won't have to wait too long for any page to load. While it is difficult to put a strict limit on file size, be aware that some older cell phones cannot load any single file with a size exceeding 1,400 bytes after processing by the WAP gateway. However, newer WAP browsers can cope with larger files and eventually everyone will have the newer phones. The WAP gateway will compress the file, but to be safe with these older devices, you should keep your text files to around 2,000 bytes, which will typically compress to about 1,400. WAP is not the Web.
Screen sizes are small, and download times are long.
Use an image only where a few words of text isn't enough. Don't rely on image alignments. Many WAP browsers support images poorly. Even though these browsers will display the images, many choose to display each image on a line by itself. This means that on certain devices you can't use images for things like bullet points or for extra text characters.