I think you want a application to automatically pick phone numbers from your contact list and send the text messages to those numbers? Then it can be done using GSM modem and your phone can be used as a GSM modem.
Using GSM modem ,messages can be sent using a application that was setup in your computer
The mechanism is what application establishes a link with the modem(your phone), collect the data from contact list automatically and format a message,then those messages are sent through the modem (your phone).
I have developed similar software before in java, for a small level financial institution. With previous experience, I can deliver you to a solution that you required.
If you want further details please contact me.
Thank You.