One-way audio behind Mikrotik

Hi Team, one of my clients; whom I am an Internet provider and also I the one who provided them the Telephone system where I used Yeastar PBX like I always prefer, they had an issue with their physical lines (POTs) with one of their providers, so they introduced me to this provider and we agreed on the Voip setup, so we are using Peer Trunk. They have a tunnel that leads straight to the Router and the communication is perfect from my side(client) to theirs, just voice. We have been playing around peering with different IP’s from my client’s side but we never have a successful call; I have realized that they follow lots of procedures before making any changes from their side; as a single change may take up to a week or two, it’s getting boring honestly. So here is the kind of setup we have at the moment from my client side:

PABX – Yeastar S50 (Version


IP =

Gateway =



               Nat Type = External IP Address

               External IP = : 5060

               Local Network Identification = /

               Nat Mode = Yes


               UDP Port = 5060

               RTP Ports = 10000 - 12000

ROUTER/FIREWALL – Mikrotik Rb951


      on bridge1

      on bridge1


               Chain = dstnat, DST.Addr =, DST.Port = 10000 – 12000 & 5060, protocol = udp,

               Action = dst-nat, To Address =, To ports = 10000 – 12000 & 5060

SIP HELPERS = Disabled


Right at the moment I know for the fact that using IP does not make sense, it was actually on the WAN port of the PABX and it was used to peer and we had problems with it, so since it’s always the hustle for them to make changes, I decided to take that IP and use it on the router instead and NAT with it; but some of the packets from the sbc (Voip Provider) want to communicate directly with the PABX( instead of the IP they know( and they get lost, (ICMP destination not found from the clients router while sniffing the call). (We are not using the public IP since with the tunnel from the client side to the Voip provider)

From a cellphone, I can call their number and it goes through, well; they can pick-up and hear me, but on my side(Cellphone) No incoming voice.

Another issue I picked up is that from their side(Client), it’s impossible to dial out through this trunk, it just drops without even going out. Please assist. What am I doing wrong?


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