I would imagine you can set up 'roaming' but I'm not sure how.
-By sending a short message
Type in ULUSLARARASI, ULUS, ROAMING or ROAM and send to 2222 by SMS to find out if your line is activated for international calls or not. If your line meets the required criteria to make international calls, you will be called back for the confirmation* of the ID details and the procedure will be completed. Otherwise, your line cannot make international calls.
Charging: Messages sent to 2222 and error messages sent from 5555 are free of charge. For Turkcell postpaid line users, the service price of information messages sent from 2040 is 2 short messages.
Note: In order for the line to be activated for making international calls, the application must be done by the owner of the line.
2-By calling Turkcell Customer Services at 444 0 532
By calling Turkcell Customer Services at 444 0 532, you can activate your line to make international calls.
This activation can be done only by the legal owner of the line.
3-Through Turkcell Communication Centers.
By visiting a Turkcell Communication Center with required documents, you can activate your line to make international calls.
Note: For the transactions done over Turkcell Communication Centers, a certain charge may be collected based on the recommendations of MOBISAD, The Association of Businessmen Dealing with Mobile Communication Systems and Devices.
However, you can complete the procedures that do not require ‘documents' over our internet page for free or for 1 SMS by calling Turkcell Customer Services at 444 0 532.
4- In case of TurkcellMobilimza owners, through Online Services Center
To activate your line to make international calls by using your mobile signature.