All the items arrived are the subject to customs clearance whether they declared or not.
There are inspectors (aka customs officers) specialized in mail traffic. They should have specific English or French knowledge. They are the persons-in-charge for deciding for the items. Not any of mail personnel are entitled to do this!
If your item is subject to customs duty after the inspection based on the declaration and the invoice attached, then you can learn the fees to be paid on the Ptt tracking webpage from now on. If none of above is available, depending on the inspector’s initiative, it is also possible to invite you to the delivery center to discuss further about the item. It will be handy to bring some proof such as an online payment printout, etc.
Also, a Call for Delivery sheet (Turkish only) is sent by mail to the addressee. You don’t have to wait for that, since you know the tracking no. already, as it takes some time to arrive. You can find the address of the correct delivery center to pick up your item in advance. Call your post office or Ptt (Turkish only) to get more information. In fact, that sheet gives all the information you need.
Below is a sample of the fees seen on the webpage. Here you see the result of an item passed the customs. So, for this item, you should wait for the delivery by a postman/-woman. Please be ready to pay the small amount. No further action is needed!
In recent years, TURKISH POST made a great attempt to modernize all its services, and it shows. The international traffic especially has worldwide standards.
DO NOT ATTEMPT TO SEND ILLEGAL ITEMS, ALL MAIL PIECES HAVE MONITORED! IN A FAILURE TO DO SO, YOU AND YOUR RECIPIENT MAY BE CORRECTED BY THE APPROPRIATE LAWS OF THE COUNTRIES!