Hello Mike
You should have the modem discovery parameters.. this is done through the "modem autoconfigure discovery" command.. This is what I have in my 3640 router for dialin connections using E1 controllers.
line 33 56
exec-timeout 0 0
no flush-at-activation
script modem-off-hook offhook
script callback callback
login authentication local
modem InOut
modem autoconfigure discovery
no exec
transport input all
autoselect ppp
Hope this helps.. all the best...