serial port is looped back

[Michael Leone <turgon@pil.net>]

Hello all.

Having a problem with ppp 2.2 on Slackware 3.5 (kernel 2.0.35).

I was setting up ppp, and noticed that I was connecting at 38400. Having a
56K modem, I figured I would enter

setserial /dev/ttyS0 spd_vhi

to increase the port access speed.

Now, when I issue ppp-on, I get this (end of /var/adm/messages):

Nov  1 22:03:35 minas kernel: Serial driver version 4.13 with no serial
options enabled
Nov  1 22:03:35 minas kernel: tty00 at 0x03f8 (irq = 4) is a 16550A
Nov  1 22:03:35 minas kernel: registered device ppp0
Nov  1 22:03:36 minas pppd[118]: pppd 2.2.0 started by root, uid 0
Nov  1 22:03:37 minas chat[124]: timeout set to 45 seconds
Nov  1 22:03:37 minas chat[124]: abort on (\nBUSY\r) 
Nov  1 22:03:37 minas chat[124]: abort on (\nNO ANSWER\r) 
Nov  1 22:03:37 minas chat[124]: abort on (\nRINGING\r\n\r\nRINGING\r) 
Nov  1 22:03:37 minas chat[124]: send (rAT^M) 
Nov  1 22:03:37 minas chat[124]: expect (OK) 
Nov  1 22:03:37 minas chat[124]: rAT^M^M 
Nov  1 22:03:37 minas chat[124]: OK -- got it 
Nov  1 22:03:37 minas chat[124]: send (ATH0^M) 
Nov  1 22:03:37 minas chat[124]: timeout set to 45 seconds
Nov  1 22:03:37 minas chat[124]: expect (OK) 
Nov  1 22:03:37 minas chat[124]: ^M 
Nov  1 22:03:37 minas chat[124]: ATH0^M^M 
Nov  1 22:03:37 minas chat[124]: OK -- got it 
Nov  1 22:03:37 minas chat[124]: send (ATDT386-3216^M) 

I don't actually dial out here; it just resets the modem (love those
external modems; gimme those little flashy lights anyday! :-)

Nov  1 22:03:37 minas pppd[118]: Serial connection established.
Nov  1 22:03:38 minas pppd[118]: Using interface ppp0
Nov  1 22:03:38 minas pppd[118]: Connect: ppp0 <--> /dev/ttyS0
Nov  1 22:03:41 minas pppd[118]: Serial line is looped back.
Nov  1 22:03:41 minas pppd[118]: Connection terminated.
Nov  1 22:03:41 minas pppd[118]: Exit.

Any idea what I did, and how to undo it, so I can dial out again?