Hey Guys!
I hope someone can help me out.. I have a few voip handsets behind a mikrotik and I was having trouble getting them registered. I disabled sip in ip->firewall->service ports and then the phones registered successfully but only outbound calls work.. something is blocking inbound calls. My handsets along with a PC are on Bridge1. Any help would be greatly appreciated.. a pic of my firewall filter/nat rules can be found here:
http://imgur.com/OiXwoLn
http://imgur.com/3BxDEvE
Thanks!
Are you using load balancing? Are you registering to a company PBX behind a firewall or to a paid service?
One way audio problems are often from NAT or PAT.
In the SIP protocol, your phone will tell the PBX which port it’s listening for inbound audio, and what ports it will be sending audio out, as well as it’s local IP (likely the private IP of the phone). Your router may change the port of the audio connection, and thus breaks the connection.
The SIP service is supposed to remedy all this by reading the SIP packets. When your phone sends a SIP packet containing it’s IP and ports, the sip helper will modify this packet and replace the phone’s private IP with your WAN IP, and dynamically forward ports for audio. If the router will do port translation, then the sip packet will be updated with those ports.
Some phone companies recommend turning off SIP helpers in your router because many vendors have broken implementations. Mikrotik’s implementation works. I’d recommend leaving the SIP service enabled and troubleshoot whatever issues remain. What were the issues with the sip service enabled?
When using the SIP service, you should also NOT use the stun service. Go into your phone’s config and remove the stun server address (if there is one). What brand and model of phone? The STUN service was a way that a device could predict port translation and obtain your public IP.
With the SIP service enabled, you don’t configure any NAT. As long as your phones register every 2 minutes then registration should just work. Is your Mikrotik behind another NAT device? Like an ISPs provided modem/router?
Finally, the ultimate troubleshooting step would be to use the packet sniffer tool in the Mikrotik. Set the packet sniffer to output to a file. Turn on the packet sniffer, place a short phone call, hang up, and turn off the packet sniffer. You can read that file with Wireshark. If you’re not familiar with the SIP protocol, you can post that file here. Your registration password may be visible.
In addition to the response above, maybe check this out:
https://www.youtube.com/watch?v=tM7wyKdnIKA
I don’t know anything about SIP other than when I saw this presentation in Denver. This guy makes it really easy to follow.
this is what helped me:
/ip firewall connection tracking set udp-timeout=300s
/ip firewall service-port disable sip
Thank you all for the replies! It ended up being an issue on the PBX side… all I did was flip NAT to ON in the extension list!
Thanks again guys; this community rocks!