How can I dial a phone number on the command line?

Put what is called a ``generic'' entry in your /etc/remote file (see remote(5)). For example:

    tip115200|Dial any phone number at 115200 bps:\
            :dv=/dev/cuaa0:br#115200:at=hayes:pa=none:du:
    tip57600|Dial any phone number at 57600 bps:\
            :dv=/dev/cuaa0:br#57600:at=hayes:pa=none:du:

Then you can do something like tip -115200 5551234. If you prefer cu(1) over tip(1), use a generic cu entry:

    cu115200|Use cu to dial any number at 115200bps:\
            :dv=/dev/cuaa1:br#57600:at=hayes:pa=none:du:

and type cu 5551234 -s 115200.