What lead you to reading about, "no default route" in the tutorial? I'm a little curious because you said you were getting a connection failed message and I assume that the modem hangs up at that point, in which case you aren't quite at the point where you troubleshoot routing tables yet. Anyhow, you should have a route for at least 127.0.0.0 when you run /sbin/route -n, so please post your output from ifconfig -a. Yes it should have the 127.0.0.0 but you don't fix that by manually adding any route entries. When the TCP/IP networking in Linux is loaded correctly, it will automatically add the correct entry.
Also, did you run any sort of configuration utility or did you manually edit the options file for ppp? If so, please post the contents of that file (xxx out your username if you wish.)
As for something to try, in your ppp options file you should have an entry that says user or name with your username for the connection. Try to change it from name to user, or if it says user then change it to name, and see if that helps. Lastly, I had some problems with the whole pap/chap thing before and what I ended up doing was putting the correct entries in the chap-secrets file and then deleting the pap-secrets file and linking a new one to chap-secrets (ln -s chap-secrets pap-secrets) and this may help you too.
Code:
root@linuxbox:~# cd /etc/ppp
root@linuxbox:/etc/ppp# cat chap-secrets
"user@isp.com" * "mypassword"
root@linuxbox:/etc/ppp# rm pap-secrets
root@linuxbox:/etc/ppp# ln -s chap-secrets pap-secrets