Does anyone know a program for bulk sms-mailing?

Question

SMS

Good time.
There is a need to send 300 - 400 SMS per month, in three or four appointments. There are no problems with the SMS themselves, 10 rubles - 100 SMS per day on Megaphone.
How to make a mass mailing program.
A free option is desirable, in any form, even sending via a phone connected to a PC.