linux ppp GPRS拨号问题

我采用了论坛上一位大侠的方法实现PPP拨号，AT命令也是通的，但是PPP数据交互总是不行 ，不知道什么原因？望哪位大侠帮小弟一个忙！！ 我的log 信息如下：
[root@liuchiqi ppp]# pppd file gprs
pppd options in effect:
debug debug             # (from gprs)
kdebug 7                # (from gprs)
nodetach                # (from gprs)
dump            # (from gprs)
noauth          # (from /etc/ppp/options)
-chap           # (from gprs)
user foo                # (from /etc/ppp/options)
papcrypt                # (from gprs)
/dev/ttyS0              # (from gprs)
115200          # (from gprs)
lock            # (from /etc/ppp/options)
connect /etc/ppp/gprs-connect-chat              # (from gprs)
disconnect /etc/ppp/gprs-disconnect-chat                # (from gprs)
-crtscts                # (from gprs)
local           # (from gprs)
noaccomp                # (from /etc/ppp/options)
asyncmap 0              # (from gprs)
nomagic         # (from gprs)
nopcomp         # (from /etc/ppp/options)
receive-all             # (from gprs)
novj            # (from gprs)
novjccomp               # (from gprs)
ipcp-accept-local               # (from gprs)
ipcp-accept-remote              # (from gprs)
noipdefault             # (from /etc/ppp/options)
defaultroute            # (from gprs)
:               # (from gprs)
noccp           # (from /etc/ppp/options)
nodeflate               # (from gprs)
Press CTRL-C to close the connection at any stage!
defining PDP context...
AT
OK
AT+CGATT?
+CGATT: 1

OK
AT+CGATT=1
OK
AT+CGATT?
+CGATT: 1

OK
AT+CGDCONT=1,"IP"
OK
AT+CGQREQ=1,0,0,3,0,0
OK
AT+CGACT=1,1
OK
waiting up to 2 mintues for connect...
CONNECT
ATDT*99***1#
CONNECT
~^?}#@!}!}#} }9}"}&} }*} } }'}"}(}"}%}&K}&}7K}#}%B#}%1}3~~^?}#@!}!}#} }9}"}&} }*
} } }'}"}(}"}%}&K}&}7K}#}%B#}%1}3~~^?}#@!}!}#} }9}"}&} }*} } }'}"}(}"}%}&K}&}7K}#}%B#}%1}3~~^?}#@!}!}#} }9}"}&} }*} } }'}"}(}"}%}&K}&}7K}#}%B#}%1}3~~^?}#@!}!}#} }9}"}&} }*} } }'}"}(}"}%}&K}&}7K}#}%B#}%1}3~~^?}#@!}!}#} }9}"}&} }*} } }'}"}(}"}%}&K}&}7K}#}%B#}%1}3~~^?}#@!}!}#} }9}"}&} }*} } }'}"}(}"}%}&K}&}7K}#}%B#}%1}3~~^?}#@!}!}#} }9}"}&} }*} } }'}"}(}"}%}&K}&}7K}#}%B#}%1}3~~^?}#@!}!}#} }9}"}&} }*} } }'}"}(}"}%}&K}&}7K}#}%B#}%1}3~~^?}#@!}!}#} }9}"}&} }*} } }'}"}(}"}%}&K}&}7K}#}%B#}%1}3~
NO CARRIER
Connect script failed