Hello Mikrotik-community!

SIP Voip and NAT is really a pain. I tried to get VOIP to work since weeks now (unsuccessfully) and I hope anyone here can help me.

My RB3011 is connected behind an Internet Router (FritzBox 7490), which provides the SIP functionality. All clients are connected to the Routerboard, WiFi with Capsman over hAP.
(Network topology: WAN ---> FritzBox7490 ---> Mikrotik RB3011 (Eth1) ---> Clients)

I activated the SIP Helper of the RB with Ports 5060, 5061, 5090, 7078,7079. Voice calls are initiated correctly, speech quality is good - but after 30 seconds the call is dropped everytime.

I would be really glad about a feedback to find a solution!

Best regards,
Alex

Hello,

all I can offer is to say to disable the SIP helpers on both the Mikrotik and Fritz box.

Everything I seem to read suggests disabling the helpers.

Ok, I'll give it a try. Disabling the (blackboxed) SIP helper might be a solution.

But now I need some help in configuring the firewall correctly! I think there is a problem with the NAT now. First of all, I disabled all rules in RB to the FritzBox. The SIP clients are connected and calls are initiating right, no dropped calls after 30sec. But now there is no voice transmission anymore - silence. I'm quite new in the Mikrotik world and I'm still unexperienced regarding the firewall rules.

Which would be the right approach to configure the FW for VOIP connection? Thanks for any hints in advance!

Hello again,

I have never tried this sort of thing with a Mikrotik behind another box.

In my cases, the Mikrotik is connected directly to the internet and the PBX is behind it.

I have the standard NAT config on the Mikrotik, but nothing special in the firewall. Everything seems to work fine. In my case I am using a SIP trunk provider for the PBX behind the Mikrotik.

Not sure exactly how you are setup.