Upvote:0
Provided he was acting in an official capacity, you have very little recourse and his actions were lawful. While annoying, what you describe doesn't sound unusual or especially invasive. It may have been a Government owned or sanctioned phone.
Transit zones are still in the sovereign territory of the host country and you are subject to their laws and border controls, including inspection. Keep in mind, not all Passports can use a Transit Zone so you don't have any 'right' to not be checked.
Upvote:3
Generally, you have the right to decline any such activity, as you have the right to not answer some or all question. However, the officer has the right to deny you entry, and it probably would be the immediate consequence, so you should consider if you want to execute your rights.
Note that you have no right to be admitted, and he can do anything that the law of his country allows, which is typically a lot, before he admits you.
Technically, even if he asks you for something clearly illegal (like having sex with him), or does illegal things, and you raise a stink, you might still be rejected and removed from the country. You can sue the country, and maybe you win, but you might well not be allowed to enter on that day, or ever.