Can not hear voice between Asterisk and HuaWei?

Hello, Guys:
I implemented asterisk for customers last week. I could connect to Huwei and two phone ring. but we could not hear each other. the IP for asterisk is and Huwei has a public IP with 211.XXX.XXX.XXX. I set a Ranch network box to map the IPs. I guess maybe there is NAT issue among two servers. Anyone knows this issues? please give me a help! thank you!

Do you have NAT=yes, externip= and all the ports being forwarded. I have seen a lot of “good routers” make issues but from what I have heard they are supposed to be real good.