Activating on iphone 7 plus sim card

They would activate the same they normally would. You erase the phone using the instructions in this support document, What to do before selling or giving away your iPhone, iPad, or iPod touch - Apple Support, then the new owner gets their own SIM from their carrier, inserts it in the iPhone and activates it by following the instructions on the screen. Set up your iPhone, iPad, and iPod touch - Apple Support

Well, since I'm in the US, I couldn't answer that question. The person you sell the device to has to deal with their carrier to ensure they have an active SIM. With an active SIM, they can insert it in the iPhone and then follow the steps in the link I provided.

finboyhelsinki wrote:

So I dont need to contact to my carrier to unlock nothing? I Only empty the device right way?

Is there any apple scandinavia support forums? thanks!🙂

The only reason the phone may need to be unlocked is if it is locked to the carrier and the person you are selling it to wishes to use another carrier. I'm not sure if all phones in Finland are locked. That is a question your carrier would need to answer. Like was provided in the link I posted, that details what you need to do when you sell/give away a device.

No, there are not Scandinavian forums.