[SR-Users] Connecting Two OpenSER machines

[SR-USER]

Hi everyone.

I have two machines running OpenSER, one machines runs OpenSER A and the other runs OpenSER B.  Phone A registers in OpenSER A while Phone B registers in OpenSER B. I would like to allow Phone A call Phone B, but not the other way around. I am a newbie so sorry for my lack of knowledge. Would should be my configurations files for OpenSER A and B?

Thanks in advanced