Hi, Assalam u alaikum.
You wrote you need a sms software that can send sms to all networks.
I made a similar project an year ago.
1) Let me know do you wish to send the SMS through mobile phone connected with your PC through a USB cable. It can be done through serial communication.
2) If you wanna send it through some gateway, you have to purchase it with yearly premium.
3) In Pakistan most of the SMS marketing is done through SMS marketting software that connects a mobile phone with a SIM card having huge SMS bundle. The types a message, select the contact list either from phone or excel sheet. Click send and with in a blink the message is broadcasted to all the recipients list.