How many iphone6 I can have with me through customer?

I'm going to Europe, and I have 3 iPhone 6 for my friend and parents. So what is the maximum number of having in order to pass the custom in USA and EUROPE? I appreciate it so much!

One.

One, your own… You have to declare any that are not for you so all three will have to be declared or you are smuggling and you have to pay import duty on them… If you do not declare all of them are likely to be taken and disposed of and you will be back home on the next flight without getting out of the airport