56k modem thru airport?

Can I run the phone line into an airport extreme base station and get internet connect on G4 via ethernet and macbook via airport wireless?

Yes that is why it has a 56k modem built-in.

You should have no problem connecting your two macs with ethernet to the AirPort, wireless to the AirPort and let the AirPort handle the dialup connection.

The phone modem setup is really quite simple. Crack open AirPort Admin Utility and click the "Internet" tab. Select Connect Using Modem v.90 and enter dialup connection numbers, user name, password all that fun stuff!

Your two macs will get DHCP and DNS through the AirPort and they will connect happily, slowly, ever after. Remember that even though you are mixing all three connection modes (wireless, ethernet and dialup) each device plays its own role.

And you will be administering the AEBS via ethernet cable for the most part;
so a non-wireless machine can be used directly to administer a network
and still get a connection through the AEBS's dialup modem; if needed.

[I used an AEBS for a few years on dialup and then got slow DSL. Can't say
as it's an improvement; but some days the IP is dead in the water and costs
alot more. Few options make everything cost unnecessarily more here.]

Be sure to check the 802.11b/g settings on the base station so you can
access the dialup if you have the newer and older wireless protocols. If
you have only AirPort Extreme (11/g) you can select for just that kind of
a network; but any visiting friends with the older 11/b won't be able to see it.
11/g is faster. You can also use wireless printing, if your printer is supported.

You would have to go into the Airport Utility and check/change the dialup
configuration setting; there will be a checkbox to make the default not
dial automatically to connect. You would have to be sure to not have
any browsers set to seek a home page and be aware of internet-on-
demand applications that seek the internet when you don't want the
computer to go attempting to dialout.

(I may look into AirPort Utility to see how I have mine set; that part
should be alot like the dialup settings in the computer, since you
can also choose to not allow the computer to dialout by itself, too.)

In the AirPort Utilty's (after you access base station w/password) header
you can click "Internet" then you can choose to have the checkbox by
"automatically dial" unchecked or checked that should do it.

Also be sure to not have the Date & Time control pane in System Prefs
set to look for a network server all the time; or it may try to have your
computer dial out when you are wanting to use the phone. It may not be
an issue, except there may be error messages in the computer when it
can't get the internet automatically for content normally supplied from there.

If you have the airport icon so it will appear in the main menubar, you can
always shut off the 56k modem from a computer via wireless. Since I am
running on battery now, I will probably have to revisit this question after a
bit or via another computer (since portable will go to sleep soon and I will
recharge it.)

When you access the AEBS, use password you set to access it, then
go into the AirPort via the Utility, and click on the button (second one
from left?) says Internet on it... you can go in there; you may see a dif-
ferent configuration than wireless airport; it can show you Ethernet or
others, so click on that if you don't see the dialup settings.

And from there, the dialup settings and where you entered the ISP
password and dialup account info should also be seen. 5% power now
so I'm signing off...

There should be a "Show AirPort Status in Menubar" check box in the
computer's System Preference> Network> Show: [Airport] and after
the Show part, you can choose several things; choose the second AirPort
so, you may see in the Network panel Location: Automatic, Show: Airport,
and the next row of buttons, should be clicked to show AirPort with the
Airport ID number and "by default join" and below that, Show AirPort Status.

Some settings can be changed without having the Airport turned on; the
"Show AirPort Status in Menubar" will appear as a working checkbox;
even if the Airport (in computer) is turned off. The Airport off/on in here
does not turn off/on the actual base station, just the computer's wireless.

PS: If you are running an older OSX version in your ethernet
connected computer that will be administering the AEBS by wire
you may hold off awhile on the updates that affect AirPort; but
you will have to be sure to update (and take your chances; see
if macfixit.com still has working links to basic airport troubleshoot-
ing in their front page; or check the hardware support in Apple
Support for AirPort Extreme.) I administer my AEBS from wire
while I also use it wirelessly, from an iMacG4 with 10.3.9; it is
up to date. My iBookG4 has 10.4.8 and it all seems to work OK.

+ + + +
We're set to expect some 45 to 80 MPH winds in this region; with rain at
lower elevations and more snow in the local ranges; farther north is more
closer to winter, like the mountains are getting here. Leaves are almost
gone and smaller shrubs are also shedding their summer/autumn glory.

Well, I see it; in my iBookG4 running 10.4.8; and you may have to click on
the selection button (where I referred to the Show: [ - - ] selection box.)
If you are seeing a different screen at that point, you did not select AirPort.

The screens are a little different between OSX 10.4.8 and 10.3.9, but both
do show the specific information in the same page as I specified. You may
be looking at the Show: [ Network Status ] window; so click on the box
where Network Status appears and in there you will see alternatives, and
one is AirPort. If another screen appears in there, (a button bar appears,
in the AirPort window if you chose to arrive there as I suggest) you can
click on the far left AirPort button to see the dialog box with the AirPort
ID number of your configuration (even if your computer is attached to
Ethernet with AirPort in it turned Off) and in the bottom of that screen
the checkbox you can toggle says, "Show AirPort Status in Menubar."

Same in OSX 10.3.9; close enough for either system user to find it there.

The only other thing is in reference to another item in that show:
box, where you have to be certain your Network Port Configurations
include AirPort, Ethernet, and whatever else you would use.
Sometimes by not checking AirPort in there, you won't see
AirPort in the Show: [ AirPort ] box; it won't be in the choices.

There should be a "Show AirPort Status in Menubar" check box in the computer's System Preference> Network> Show: [Airport]...

That is incorrect. If you are connected via Ethernet, the Mac knows nothing about AirPort. There will not be an AirPort item in the menu bar.