Everyone still using their cellphones. It was a toy of the rich a scant five years ago, now average people have them. They get cards with credits from supermarkets and call them in. If they call someone with the same company it is very cheap, just over a penny a minute. Out of system people are ten times more.
With personal income a tenth ours, that's understandable.
Once the seond/third world gets a taste of cell phones, they don't give them up. What they do in hard times is migrate to prepaid plans that charge in increments as low as one second. TKC offers those plans, but management states that this type of service isn't as profitable.
That said, I think that TKC is positioned to prosper in the long run offering service in Asia Minor, and in the future in the Middle East, Syria and Iraq. The have a relatively low overhead plus the cultural connections established during the Ottoman reign. In the short term, it could be rough, but I'd look at that as a buying opportunity.
TKC was cash positive in dollars last year despite expansion and devaluation of the Turkish lira. They also have very little debt in comparison to other cellular companies.