Symptoms:
Customer has a sip conferencing product “LifeSize Express 220” that is able to register with the sip server, receive incoming calls, but cannot call out. The customer has other SIP products including there primary phone system which uses the same default port (different public IP) and has also tried many different SIP providers with the same result.
Environment:
Network Involving many different model Mikotiks (RB1100x2, Cloud Core, x86) all running version 6.5 and higher using OSPF for routing. This customer is 5 hops out from the internet. 3 Network hops, then our firewall and gateway interfacing to our upstream providers through BGP. All devices are running Router OS.
Action Taken\Troubleshooting:
Using the torch feature of the router OS we’ve been able to determine that when the customer attempts to make an outgoing call, we can see a TCP session is established with bidirectional traffic to the sip server. Then we see a UDP session going out from the customer, it makes it to the second hop on our network and dies. On the second device I can see the UDP session coming in on the ingress port but it doesn’t not leave on the egress port. I checked all firewall ACL’s and turned on logging for everything the ACLS are dropping and nothing regarding the affected IP is being dropped. We even put in a UDP allow all ACL inbound & outbound which didn’t have any effect. We then thought that maybe there was something different in the config for this device so we put in a static route to allow the customer’s path to route around this device and we got the same result goung through a different path on a different Mikrotik. With the static route in to take a separate path (1srt hop is common), the second hop I was able to see the UDP session on the ingress port but not on the egress port.
The customer was able to take the SIP device home with him and plug it into his TW cable modem and it worked no problem. I have done a bit of google searching and I haven’t been able to find a reference to Mikotik\Lifesize together. Someone has had to run in to this issue before. This is my first time posting, please let me know if this is in the wrong section or in an incorrect format. I’m sure you might need more info to help me out, just let me know what you need.
Thanks!