Ensuring SFC for phone calls

General
1

I have a B One with multiple WAN sources and our phones are connected to the B One’s WiFi using WiFi calling. How can I ensure that phone calls are using SFC? What do I need to verify in the Active Sessions to know if it’s indeed working for phone calls?

Thanks in advance.

2

You will need to use your outbound policy and ensure you’ve identified the mobile devices in a way to route them using OBP. You can do this a variety of ways that you will see when configuring OBP. From there, you can look at your active sessions to verify that the UE (phone) is connecting to whatever ePDG is being used by the UE.

The issue here is knowing where the destination (ePDG) is. The ePDG is what the UE (phone) connects to in order to enable VoWIFI. AT&T and T-Mobile used to publish this data but it doesn’t seem to be there anymore. In this case, I would look for IPSec traffic (USDP500/4500), but if you’re running other IPSec tunnels in your environment or client VPN this may be an issue. Also consider contacting your mobile provider(s) to ask them what firewall rules/destinations are needed to enable VoWIFI traffic and they may provide this to you (though most will say IPSec and every other port LOL)

In order to try and be precise without knowing the ePDG domain/IP, you could have a mobile-only VLAN (this is somewhat common in enterprise anyway now), and then route your IPSec traffic over SpeedFusion. But, be warned, that this will add additional overhead and create some MTU issues for the IPSec tunnel as it will be encapsulated in the SpeedFusion tunnel.

Hope this helps!

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3

Thank you so much for the excellent answer! I created an OBP to route all data through the SFC tunnel which worked. Then, as you suggested, I looked at the action sessions and found that it is indeed working for all the active sessions EXCEPT for the IPsec created when making a call which is going directly to one of my WAN sources (unfortunately the least preferred). I think it’s a problem with Google Voice (used on the phone for business calls) which only wants to work on Verizon, but at least I know how to use the Peplink software to do what I want now.

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