If you want to run ppp please try these setps:
setp1: install pppd and chat in your board
./install.sh
setp2: run pppd in background
pppd call wcdma_connect &
setp3: find the local ip of ppp0
ifconfig
setp3: set route default with the ip of ppp0. like (inet addr:10.24.2.223)
route add default gw 10.24.2.223
setp4: set nameserver
cp resolv.conf /etc/
setp5: test the net connect
ping www.sina.com.cn
setp6: disconnect net
pppd call wcdma_disconnect
If you want to uninstall the pppd run ./uninstall.sh