Hello PJSippers, The codec frame_out size of PCMU is 160 bytes on Win32, but it's 800 bytes on Windows Mobile! The codec frame_out size of GSM is 33 bytes on Win32, but it's 165 bytes on Windows Mobile! The codec frame_out size of Speex/8000 is 38 bytes on Win32, but it's 50 bytes on Windows Mobile! etc. Why is there a difference in the payload size between the 2 platforms? What is it due to? Regards, Elias. _________________________________________________________________ Windows Live™: Keep your life in sync. http://windowslive.com/explore?ocid=TXT_TAGLM_BR_life_in_synch_052009