How can I inetractively talk to a modem with at commands etc?

I am trying to get PPPd set up with NAT routing to connect my LAN via our static IP address with our ISP.

I've been following the instructions and templates in:
http://www.macbsd.com/macbsd/howto/pppnat/pppnat.tgz

and get the error:

macbsd: {3} /usr/sbin/pppd /dev/tty00 call telstra
/usr/sbin/pppd: The remote system is required to authenticate itself but I
/usr/sbin/pppd: couldn't find any secret (password) which would let it use an IP address.

I'm sure I just have to reconfig some file (I have already set up pap-secrets and symlinked chap-secrets to it), but I'd first like to confirm that I can actually talk to the modem.

Any help appreciated.

Thanks,
Tom
T&B