honorsly, i do not think the software based solution can solve your problem. it is true, maybe the quality of calls becomes better. yes. we offer Octasic SoftEcho, you can try that. i think the quality is same with HPEC license.
So far, we do not any have hardware based echo cancellation card. but it will come out soon. you can try the software to solve your problem. it calls Octasic. some customers said that after installing Octasic, the call became better. i can not say it is a perfect solution. at least it can help you. you can access this:http://www.openvox.com.cn/products.php?genre_id=29.