The following information was found on another forum, which (unfortunately) did not state the source.
Running a mobile phone in Turkey, even when just visiting for a short periods, is not only much cheaper than using your UK phone in extortionate roaming mode, but it also means your local resident friends will ring you more often.But the problem with running a mobile phone in Turkey is that the credit, known as kontors, can be forfeited and the number deleted unless more credit is added from time to time.
The section below, an extract from a phone account, shows the various cut off periods for a phone that was recharged on 20 June:
As of 27 June 2008 , your account is, active.
If you do not recharge
After 18.September.2008 you can still receive incoming calls but can not make any outgoing calls.
After 17.December.2008 you can not receive or make any calls.
After 16.January.2009 your account will be closed.
This has been a problem for infrequent visitors to Turkey as additional credits could only be added using the actual phone when it was connected to the Turkcell network in Turkey. The way around this was to leave your phone, instructions and a kontor card with a friend or neighbour resident in Turkey for them to update at the right time. This usually isn’t a problem but, from time to time, things can go wrong and you come back to a dead phone and an embarrassed friend/neighbour.
But now you don’t need to bother your friends and neighbours as there’s a way to add credit yourself. As long as you have an internet connection, a Turkcell phone and follow our step by step guide you'll remain topped up and connected.
So what do you need to do?
1. Send a text containing the word ‘password’ to 2222. You will receive your numerical password as a text in a matter of minutes. YOU MUST BE IN TURKEY AND ON THE TURKCELL NETWORK TO DO THIS.
2. Go to http://www.turkcell.com.tr/en
and click on the online services picture (computer mouse picture near the top of the page)
3. On the next page fill in the log in form as instructed including your password from step 1 above.
4. When you have completed the form you will then be asked to change your password. Complete that form and return to the log in page.
5. Fill in the log in form again as instructed
6. You will now see, assuming you completed the form correctly, the ’Hazir Kart’ page showing you have logged into your account.
7. Click on the ‘Counter Recharge’ menu and you can add new knotors to your account using a credit card.
We found the Hazir Kart site fairly easy to use. Most of the pages are in English but some Turkish menu items have slipped in too. It also offers many other great features such as a check yof our current credit level, cut off dates, PIN and PUK number, change the Line Services language to English, barring of international calls and much more.
Oh, and before we go it really is worth asking the ‘Tariff Laying Chicken’ which is the best tariff for you. Go to this link http://www.turkcell.com.tr/en/plans
to see what it says. Click on the picture of the cartoon chicken, wait for the window to load, turn up the volume and answer the questions. It may not find a better tariff than the one you are on but it's very funny!