I came back to Turkey with a mobile phone on 08 Jan 2015. On 06 Feb I got a text saying if I did not register my phone by 25 Feb 2015 I would be blocked.
This shows they give you plenty of warning.
The Tax was 132 TL and the Registration charge at Turkcell was 50Tl add onto that your new Sim card and that is the total cost as at 06 Feb 2015.
I had to produce my passport at the Tax office .
For Regesteration, Turkcell they needed my proof of taxing, which he kept , but gave me a photocopy back when I asked for it. A copy of my passport. When he saw my
Recidence Permit he took a photo of that aswell.