Yes,
look at Michael`s post - he is right about your switch control. For me it should look like:

while(1)
{
  SWT=1;            // init input pin
  while(SWT);       // wait till it high
  sendATCommand();  // process
  while (!SWT);     // wait till switch has been deactivated
}

But it depends on your hardware. As well, debounce must be provided either with external hardware (such 7474, etc) or by your software.

Regards,
Oleg