In Portugal, when welcoming somebody you should always remember about forms of politeness. Almost each, even the small talk by phone, begins with Olá, tudo bem?, which is the most common way to greet people in Portugal. It´s used here like a beginning of conversation, no matter if you talk to your close friend or somebody that you just met. It works with person on the phone, family, friends, colleagues and moreover.
Tudo – everything, all
Bem – well
The meaning is Hey, how are you?/Hey, all good?. The most common way to answer is very easy – Tudo (All – so the confirmation that everything is fine), without any additional details, complains or whatsoever. You can also be nice and ask E tu? or E vocês?.
For some people it might be suprising that the standard answer almost always is positive Sim, tudo bem. E tu?, even if it´s far from the truth. In brief: Portuguese, even if they complain it´s always after this initial exchange of politeness and ensuring that everything is ok.