To make this change using OT/PPP, you need to modify the modem script. For those wanting to give this a try, I have posted a MacFixIt Extras web page where I describe exactly what I did. I have no official confirmation from Apple that this is the correct way to do this, but it worked for me. Try at your own risk.
Several readers offered other suggestions for fixing speed-related problems with this modem. Here is a sampler of what they said:
Jason Whong, quoting a message from Apple's Joe Azzato: "You can simply enter the string such as 'at ms=10,1,1200,33600' which tells the modem to connect as fast as it, can between 1200 and 33.6 baud."
Will Brown writes that postings on O'Grady's PowerList claimed that selecting the 3COM Impact Analog 14.4 script, rather than the one for the 3400 internal modem, increased performance speed.
Chuck Mobley suggested trying SerialSpeed 230 v1.7. He was having speed problems on a different modem and installing this solved them.
Spontaneous disconnects By the way, I also tried enabling both the "Allow error correction..." and "Use TCP header compression" options in the PPP (or Remote Access, if you use ARA 3.0) control panel - rather than selecting one or the other. Again, this is a subjective impression only, but it seemed to help prevent the spontaneous disconnects that still plague my system.
International versions of the 3400 O'Grady's PowerPage has been covering issues relating to differences in the modems that ship with international versions of the PowerBook 3400.