How to send AT command to modem in adb shell

1. try to find AT command tty in adb shell, AT command tty is named by smd[num] and from radio group
sdm710:/ $ ls -al /dev/smd* | grep radio
crw-rw---- 1 radio radio 245, 7 1970-01-01 21:17 /dev/smd11
2. use below command to write/read AT command port:
cat /dev/smd11 &
echo -e "AT+CFUN=?\r\n" >