The UART is an internal one inside the SA1100 - it's not really like anything else, they just claim 16550-ishness as it has FIFOs (though they're not as deep as the '550 - I think it's 12 on RX, 8 on TX from memory).

Your CDPD modem - can you enable Xon/Xoff flow control and set your PPP asyncmap to make sure it doesn't use these characters? This would solve the problem.

The reason only data is wired to the docking connector is simply the docking connector: it only has 16 pins and these have to carry 4 audio outs, 2 audio ins, antenna, power, *and* serial.

Hugo