ssparikshya: please don't refer to any of us a "SIR" we all are buddies here.
those who are seniors love to be called buddies as it makes them feel younger
and those who are younger, also love to be called buddies to get company of the senior without problems.
I trust your invite thing, but of 3 invites (2 of USA ones, and 1 of India ) I've got till date never needed this step, or I never tried it, it would have been done
by those persons whom I gave them.