We having an issue with our VOIP that is behind an NSA 2650.
We have an Lync 2010 that is behind an NS 3650. The NS 2650 has an site to site VPN to NS 3650. The VOIP is working correctly between the sites or when someone calling from external location to both sites.
Problem is when someone using an skype for business app and try to call someone in the site of NSA 2650. Connection is made but no voice go through. When call from the same external location to a Phone in the NS 3650 no problem there.
The company that responsible for the lync says that the NSA 2650 block the udp connection, but in the NSA 2650 I dont see anything coming from that external location.
Any tip on how to check the logs to see if really udp get dropped?
I am not sure if the packet is coming from a different IP after the connection establishment making no packets to come through or there is something blocked on the ISP end.
But here are a few things that you can try on NSa 2650:
1) Exclude the phones from App control.
2) If that does not help, create LAN to WAN and LAN to VPN access rule and vice versa including the ports mentioned in the link from Skype and disable DPI inspection
3) Perform packet capture for the internal IP address of the phone and check if there are any drops.
Honestly it would be best to perform some real-time troubleshooting to compare both working and non-working scenarios to find the root cause.
Technical Support Advisor, Premier Services