You create .txt file with sms numbers, .txt file containing one number per line.
Copy.txt file to internal SD card on your phone.
Select .txt file.
Write your message and save.
Set seconds interval betwen sending SMS and save it. - 38 sec (to complain 100 messages per hour limit).
If phone sends more then 100 sms per minute Android system STOP sending SMS - to avoid this you must root your phone i enable more SMS per hour then 100.
Tap on START/STOP and message sending begins.
Tap on START/STOP to PAUSE sms sending.
Tap on RESET/SET to reset counter to zero (or input som other numer) and enable new sms sending.