ppp拨号后无法ping通外网

我在linux2.6.9的平台上用了一个gprs的modem来拨号，拨号成功后也给分配了ip地址（10.61.23.12）,peer ip为10.0.0.1，也分配了dns(211.2.65.3)
这时候可以ping通10.0.0.1,
然后将ppp0接口做为缺省网关：
route add default dev ppp0
这时候再ping 211.2.65.3，却返回no response from 211.2.65.3.
请问这是什么原因，如何解决呢？（我想这肯定不是路由的问题）


PS:

ppp-on:
#!/bin/sh
#
# Script to initiate a ppp connection. This is the first part of the
# pair of scripts. This is not a secure pair of scripts as the codes
# are visible with the 'ps' command. However, it is simple.
#
# These are the parameters. Change as needed.
TELEPHONE="*99***1#"
ACCOUNT=CARD
PASSWORD=CARD
APN=CMNET
LOCAL_IP=0.0.0.0
REMOTE_IP=0.0.0.0
NETMASK=255.255.255.0
export TELEPHONE ACCOUNT PASSWORD APN
#
# This is the location of the script which dials the phone and logs
# in. Please use the absolute file name as the $PATH variable is not
# used on the connect option. (To do so on a 'root' account would be
# a security hole so don't ask.)
#
DIALER_SCRIPT=/etc/ppp-on-dialer
#
# Initiate the connection
#
# I put most of the common options on this command. Please, don't
# forget the 'lock' option or some programs such as mgetty will not
# work. The asyncmap and escape will permit the PPP link to work with
# a telnet or rlogin connection. You are welcome to make any changes
# as desired. Don't use the 'defaultroute' option if you currently
# have a default route to an ethernet gateway.
#
echo $DIALER_SCRIPT
exec /sbin/pppd usehostname -detach noipdefault debug lock modem crtscts 115200 \
/dev/ttyS0 usepeerdns novj asyncmap 20A0000 escape FF kdebug 0 $LOCAL_IPREMOTE_IP \
netmask $NETMASK nodefaultroute connect $DIALER_SCRIPT


ppp-on-dialer:
#!/bin/sh
#
# This is part 2 of the ppp-on script. It will perform the connection
# protocol for the desired connection.
#
exec chat -v \
TIMEOUT 3 \
ABORT '\nBUSY\r' \
ABORT '\nNO ANSWER\r' \
ABORT '\nRINGING\r\n\r\nRINGING\r' \
'' AT \
OK ATH \
OK ATE1 \
OK AT+CGATT=1 \
OK 'AT+CGDCONT=1,"IP","$APN"'
OK ATD$TELEPHONE \
TIMEOUT 30
CONNECT ''　　　　　　

211.2.65.3 我也ping不通啊　　　　　　

sorry，没看到是GPRS的，这东西还没玩过。不过楼主把route表show一下先啊，通常ppp拨上去会自己加路由的吧。用什么工具拨号的？log有没有问题？　　　　　　

是啊，可以自己加也可以自动加的，log中没有提示有任何问题。