环境是 arm-linux (ubuntu)
在 device 上装上 3G网卡(UC20)，kernel也有抓到。接着在编辑
etc/ppp/peers/Module-UC20, /etc/ppp/peers/Chat-Module-UC20-connect,
etc/ppp/peers/Chat-Module-UC20-disconnect.
最后执行 pppd call Module-UC20出现以下讯息
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root@ubuntu-armhf:/# pppd call Module-UC20
abort on (NO CARRIER)
abort on (ERROR)
abort on (NO DIALTONE)
abort on (BUSY)
abort on (NO ANSWER)
send (AT^M)
send (ATE0^M)
expect (OK)
^M
OK