aaa authentication ppp default if-needed local
username USER password PWD
isdn switch-type YOUR-COUNTRY
interface Dialer1
ip unnumbered FastEthernet0/0
no ip directed-broadcast
encapsulation ppp
no ip mroute-cache
dialer in-band
dialer-group 1
peer default ip address pool POOL
no fair-queue
no cdp enable
ppp authentication pap
Bind this logical interface to any physical (bri, pri, ...), for example with dialer rotary-group 1.
Or, if you have async connection, you can use
interface Group-Async1
ip unnumbered FastEthernet0/0
no ip directed-broadcast
encapsulation ppp
dialer in-band
dialer idle-timeout 600
dialer-group 1
async mode interactive
peer default ip address pool POOL
no cdp enable
ppp authentication pap
group-range 65 76
where 65 76 are your modems
ip local pool POOL 192.168.0.1 192.168.0.10
and this if you have mica modems
line 65 76
session-timeout 10
timeout login response 80
autoselect during-login
autoselect ppp
absolute-timeout 180
modem InOut
modem autoconfigure type mica
autocommand ppp
transport input all
flowcontrol hardware
if you have an ISDN interface and modems, you need to configure dialer and groupasync
bye