1)How would you propose to do that with a fixed rate type of echo canceler, like OSLEC? If application can be used only with PCM/8000 call it wil be helpful for me. For other rates OSLEC source code changes may be requered. 2) Do you also believe in unicorns? ... Please accept my apologies. Now I understand what said Steve Underwood 3) The OSLEC echo canceler is blocked by licence conditions. I find it difficult to understand why the FS can use GPL Linux kernel, but can not use one of his GPL drivers (not propritory firmware driver). 4) The OSLEC echo canceler is a great addition to the PSTN interfaces - DADHI and FreeTDM - but has no use elsewhere. Could you help me to see how OSLEC uses DAHDI or FreeTDM api. Why other application cannot use OSLEC without DAHDI? Sergey.