In which airport am I expected to clear customs and immigration?

Question

I'm an Indian citizen, travelling from Kolkata to Detroit via Delhi and Amsterdam. I've a flight with Air India from Kolkata to Delhi and a flight with KLM from Delhi to Detroit, with a stop at Amsterdam. The Air India flight (AI-23) leaves from the domestic terminal at Kolkata but arrives at the international terminal in Delhi. Am I to complete customs formalities at Kolkata or Delhi? I spoke with two airline representatives over phone, and they gave different answers.

Answer 1

Immigration controls always happen when exiting or entering a country, unless you're transiting through a country without actually entering it. Therefore:

1. The Kolkata-Delhi flight will have no passport/customs control, as it's an internal flight
2. At Delhi airport you will go through Indian immigration
3. At Amsterdam airport you won't go through passport control or customs, as you're only there for transit
4. Finally, at Detroit airport you will go through American immigration control, followed by American customs, and enter the United States