Multi user / modem / sms every month

Hello , I have some questions I will list them below:

  • A Multi- user use; have multiple users each one with its own list of contacts and its own log messages sent etc.

-possibility using multiple modems so that you can configure for each user modem with which it will be able to send SMS .

-planning repetitive SMS : Program for sending SMS messages each month permanently until the user stops it.

I would like to know your property attentions or suggestions , is that these points are feasible , if this is Yes on what level we can intervene to develop these so-called points.

Thank you .