In UMTS it uses Turbo Coding and Convolution Coding.
The reason being is : UMTS should support both voice and packet data. Turbo coding will not be efficient for Packet data.
So, for Voice UMTS uses Convolution coding and for packet data UMTS uses Turbo Coding.
Turbo Coding >= 19.2 Kbps
convolution Coding < 19.2 Kbps (for low data rates i.e for voice)