I temorarily gave up authenticating by PAP on mgetty because
I suspected there to be some other problem masking this one.
So I removed "auth" from the mgetty args and tried again.

This way I indeed got a connection. And indeed, it did seem to
reveal another problem. There is a horrendous delay in this
connection: on the order of a minute and a half.

I'll write more details about the delay at the bottom of this
email. First, here are the results of calling from the ThinkPad
to the tower. (I have two telephone lines -- so can experiment
side-by-side).

thinkpad# /etc/ppp/ppp-up-gus &
[1] 2364
thinkpad# Sep 30 15:19:51 thinkpad pppd[2336]: Hangup (SIGHUP)
Sep 30 15:20:43 thinkpad pppd[2366]: pppd 2.4.0 started by root, uid 0
Sep 30 15:20:43 thinkpad /netbsd: pcmcia0: card irq 10
Sep 30 15:20:45 thinkpad chat[2369]: abort on (BUSY)
Sep 30 15:20:45 thinkpad chat[2369]: abort on (NO CARRIER)
Sep 30 15:20:45 thinkpad chat[2369]: abort on (NO DAILTONE)
Sep 30 15:20:45 thinkpad chat[2369]: send (ATDT3491327^M)
Sep 30 15:20:45 thinkpad chat[2369]: expect (CONNECT)
Sep 30 15:21:04 thinkpad chat[2369]: ATDT3491327^M^M
Sep 30 15:21:04 thinkpad chat[2369]: CONNECT
Sep 30 15:21:04 thinkpad chat[2369]:  -- got it
Sep 30 15:21:04 thinkpad chat[2369]: send (^M)
Sep 30 15:21:04 thinkpad chat[2369]: send (AT&C1^M)
Sep 30 15:21:04 thinkpad pppd[2366]: Serial connection established.
Sep 30 15:21:04 thinkpad pppd[2366]: Using interface ppp0
Sep 30 15:21:04 thinkpad pppd[2366]: Connect: ppp0 <--> /dev/tty03
Sep 30 15:21:09 thinkpad pppd[2366]: Deflate (15) compression enabled
Sep 30 15:21:12 thinkpad pppd[2366]: local  IP address 192.168.1.101
Sep 30 15:21:12 thinkpad pppd[2366]: remote IP address 192.168.1.100
Sep 30 15:21:12 thinkpad /netbsd: IP Filter: already initialized

...So, I have an IP address for each via PPP over telco lines and
mgetty. Both ends can ping eachother. But the horrendous delay I
spoke of shows up here. See below, I ping from the ThinkPad to
the tower...

thinkpad# ping -c 3 192.168.1.100
PING 192.168.1.100 (192.168.1.100): 56 data bytes
64 bytes from 192.168.1.100: icmp_seq=0 ttl=255 time=142.956 ms
64 bytes from 192.168.1.100: icmp_seq=1 ttl=255 time=106.142 ms
64 bytes from 192.168.1.100: icmp_seq=2 ttl=255 time=104.582 ms

----192.168.1.100 PING Statistics----
3 packets transmitted, 3 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 104.582/117.893/142.956/21.719 ms
thinkpad#

...But 1 minute and some 30 seconds passed between my entring
the PING command and the appearance of the line which said...
"PING 192.168.1.100 (192.168.1.100): 56 data bytes" which is not
right at all.

I suspect that this is why, when I tried to login via PAP I got a
nastygram on the ThinkPad that said "Peer refused to authenticate".
I suspect that authentication timed out.

Know further that the delay is 2-way. I have the same effect when
pinging from the tower to the ThinkPad.

What might cause such a delay?