I was buying http://ixc.ua/?MenuId=232 Lucki-E1 PSTN gateway, install driver and try to using it with askerisk.
Everything work fine, but little echo was present, bcs my device don’t have internal echo canceler. They have also echo canceler on board, but probably i can do echo canceling in askerisk?
Gateway of IXC is a little bit expensive with echo canceler on board ($700). So i like to keep current device.