I need some pointers here - I am not sure exactly what of which algorithms, a standard 28.8 modem uses. Noting that the first TCP packets are more important than later ones, based on these figures, the gain of using compression is substantial. The result may depend on how the modem performs compression and may vary depending on the size of the HTML object. However, we believe that the effect of HTTP message body compression will be positive on a PPP modem line. This test does not take into account the time it takes to compress an HTML object on the fly and whether this will take longer than the time gained transferring less bytes.
Decompression is done on the fly by the client.