We do not provide codes. We are just helping each other in the progress of development.
To send AT commands you would need a mobile phone or anything like that (a modem would do also).
Therefor you would need to communicate with the device - which is generic and can not be described in general.
So it's not that simple.
Another suggestion:
You want to communicate with some mobile service. Are they using SMS? I would guess so. So I would try this
SMS lib[
^] and develop something for this.