Echo cancelation for asterisk

Hi.
I’m using external gateway (Addpac AP200D) for connection to PSTN. I have problems with echo, during the call to PSTN.

Does Asterisk have echo cancelation feature (or some modules) that can remove the echo from the conversation?

I’m not using PCI card, so I can’t use zaptel’s echo cancelation…

I’m waiting for any advices.

Thanks a lot!!!