This describes a case where the intention of the firewall provider is to ensure all traffic of a specific type, e.g. VoIP, is blocked even though the network operator and UE uses Service Reachability.

• The network operator provides a VoIP service.
• The user is subscribed to the VoIP service.
• The UE is connected to a firewalled WLAN network that is independent from the network operator.
• The firewall of the WLAN network blocks VoIP traffic as a result of the firewall provider policy.
• The UE and network operator implements Service Reachability.
• The firewall provider blocks Service Reachability.
• The network operator and firewall provider are different entities.
• This scenario applies regardless of whether there is a business relationship between the network operator and the firewall provider.

a) The user attempts to make a voice call using the network operator VoIP service.
b) The firewall blocks the VoIP call.
c) The UE then uses the Service Reachability functionality to initiate the call.
d) The firewall blocks the Service Reachability function.

• User VoIP call attempt fails.
• The firewall provider policy to block VoIP traffic is maintained.