How can I send SMS from Mikrotik using GSM modem?

How can I send SMS from Mikrotik using GSM modem?
I did it before, but now it is not working..

[admin@MikroTik] /port> print
Flags: I - inactive

DEVICE NAME CHANNELS USED-BY BAUD-RATE

0 1:2 usb1

I used the below script:
/tool sms
send port=usb1 channel=1 message=Hi phone-number=***********

If anyone can help me then I appreciate you.