sending SMS on a batch mode

I plan to use mysmsmantra along with SMS framework to send SMS on events like birthdays and wedding anniversaries. I wrote a module to allow some options to be configured and plan to write a PHP script that can be run as a cron job. In the PHP script I would like to get the SMS mantra account balance and use the send function. But using these functions doesn't work in the context of my module.
For example the below statement doesn't work
$accountbalance = $form_state['values']['sms_mysmsmantra_balance'];

Is there a way to access your functionality. I am keen on implementing this in my module. Any help would be appreciated

Best regards

Sridhar