故障分析路由器未接地引起的無(wú)法撥號(hào)故障

故障現(xiàn)象
    筆者某次配置了一個(gè)16日的AM模塊。出現(xiàn)了一個(gè)奇怪的問(wèn)題。配置好后，撥入時(shí)沒(méi)有Modem撥號(hào)聲。只有電話的聲。并且音指示燈也不亮。當(dāng)筆者拔下模塊上的電話線時(shí)。指示燈亮了。
    [b]配置[/b]
    620#sh run
    Building configuration...
    Current configuration : 866 bytes
    !
    version 12.2
    service timestamps debug uptime
    service timestamps Jog uptime
    no service password-encryption
    !
    hostname2620
    enable secret 5 $1$pUrf$9xGOg.zyxKawi9NljLHHr1
    usernameuser password 0 Cisco
    ip subnet-zero
    !
    !
    no ip domain-lookup
    !
    !
    !
    !
    interface FastEthernet0/0
    ip address 136.0.0.254255.255.0.0
    duplex auto
    speed auto
    !
    interface Group-Async1
    ip unnumbered FastEthernet0/0
    encapsulation ppp
    async default routing
    async mode interactive
    peer default ip address pool lab