How to send an SMS with an AT command

at+cmgf=1
OK
>at+cmgs=18583373799
>> Type your message!
+CMGS: 1
OK

First, type "at+cmgf=1" to put the modem into SMS mode.
Then type "at+cmgs=phonenumber" and press enter.
Start writing your message.
When you are done, press "Ctrl+Z" to send the message.