My question is, are internal 56Kbps modems faster than external serial port
connected 56Kbps modems, when transferring highly compressible files.
The question is not relevant to USB connected modems.
I have tested a cheap internal modem and a mid-priced external modem. The
external modem was connected at 115200bps and so was the internal modem, but
I suspect the DTE speed means nothing for an internal modem. The operating
system is NT4 sp5 on a Pentium II, 300MHz.
The line speed for the internal modem was 50,667bps.
The line speed for the external modem was 52,000bps.
Using a 300KB dBase file, the throughput, using FTP, was:
Internal, 19.2KBytes/s, i.e., at least 153,000Kbps.
External, 11.2KBytes/s, i.e. at least 89,000Kbps.
The internal modem is running at faster than the DTE speed, which is why I
think that may be irrelevant in the configuration for that type of modem.
Since 115,200 is as fast as I can connect the external modem on my serial
port, it seems that internal modems will perform better on compressible
Any thoughts or comments on these results?