Do you have a call center or are you starting a call center? People do refer to this site as the India Call Center Forum. But I have seen other countries mentioned. Feel free to jump right in.
Bulgaria does have low labor costs, highly skilled work force and good techs. Most all Cental Europe does. I have been to Sofia twice but enjoyed smaller cities like Ruse, Lom and Varna more.
If you need any help with a call center, please contact me at: email@example.com. I will be glad to help point you in the right direction.