It's very hard to find a Skype beater for calls to the UK but 4p a minute to Turkey is quite good. For people with a smartphone Nimbuzz is good for calls to UK from a mobile - 1.3p/minute. From UK to Turkey about 2.2p/minute.
Friar is right though - the attraction of Lebra is no need for a PC, headphones, microphone - and no need for a cutting edge mobile - you just stick the sim card in your wooden 19th Century Nokia, and start dialling.