Hello Everyone im new in voip im working in new project and i have this toplogy
Cisco jabber -->Cucm-->Cube-->Firewall(sophos)--->INTERNET(SIP-Trunk)
the problem was the phone ringing but there's no sound in both ways and i think the problem is NAT
the firewall is sophos
the internal call is working fine but when i establish a call to outside there's no audio in both ways
which NAT should i put in the firewall
i use this NAT but it does't work
thnx
Recommend you to reconfigure your SBC (Cube) to have two interfaces. One connected to your internal network and the other connected to your firewall for the connection to the SIP service. This would be the preferred setup of a SBC for it to truly come to it’s right as the demarcation point between your internal network and the external SIP service provider.
Yes that’s correct. Anyway if the OP wants to have a firewall in front of the outside interface of the SBC to the service provider. This is not all that common in my experience, as the SBC can be setup with its own security enforcement, but if for example the connection to the service provider would utilise internet it could be a requirement for various reason.
The reason for why I would argue to have an inside interface is that there is little point in having the internal endpoints communicate with the SBC via a firewall. I mean you would not likely contemplate to do that with a TDM voice gateway, right? See it as you would for a Expressway C, you would not very likely put a firewall between that and your endpoints. There is a merit to have the interface that face the service provider behind a firewall for protection. But as you say keep clear of NAT as that's s pretty sure way of successfully creating a perfect storm of issue and shorten your expected lifespan with a few odd years or so.
True, those paranoid security folks are always “fun”. Joke aside, it would depend on what type of connection you utilities for the circuit with the service provider. If it’s a less secure connection type like internet this could absolutely be of concern.
My experience is that this is not the preference connection type for most service providers. More common would be to use a dedicated private connection to deliver the SIP service. This also in most cases removes the need to use encryption to protect the media and signaling path between the customer and the service provider. Whereas with a service running via internet this would be a necessity to protect the integrity of the traffic.
