one way audio from third vendor

Hey sir

I m using DX, i m facing a problem like, calls from two vendors r working fine but when i add third vendor, calls become oneway audio, is it like i cant accept calls from more than 2 ips.. but it works fine in my AX, i can accept calls from diffrent 5 ips..

but in dx.. i dont konw where the problem is, since i m new with dx