Hm.

For one thing, you're not reading anything, how can you even tell if the device answers? It might be waiting for data to get read from it before it'll do anything else.

For another thing, maybe it needs carriage returns, which UNIX usually doesn't provide or use. You can force echo to produce them of course...

# Open ttyS2 for reading and writing as FD 5
exec 5<>/dev/ttyS2
# Leave this running in the background
cat <&5 &
# Write a command to FD 5
echo -en "AT\r\n" >&5
sleep 3
echo -en "AT+CMGF=1\r\n" >&5
sleep 3
echo -en "AT+CMGS=\"333xxxxxxx\"\r\n" >&5
sleep 3
# Is this supposed to have a carriage return + linefeed?  Not sure.
echo -en "ciao\x1a\r\n" >&5

Sorry...the last line was:
echo -en "\x1A">/dev/ttyS2

---------- Post updated at 12:11 PM ---------- Previous update was at 12:02 PM ----------

It workssssssssssss!!!!!!! Thank you so muchhh!!!!!!!!!!!

thanks thanks thanks thanks thanks thanks thanks thanks

You are welcome. I'd love to see your complete script.