interface Serial3/0:15
no ip address
encapsulation ppp
isdn switch-type primary-net5
isdn incoming-voice modem
interface Group-Async0
ip unnumbered GigabitEthernet0/0
encapsulation ppp
peer default ip address pool dailin-pool
ppp authentication chap pap
group-range 1-30----------------------------- (1--30路电话)