I’ve found that the following works well for incoming and outgoing calls and has been very robust in poor / no cell connectivity areas so that I can bond multiple services and keep a call going even when one of the services drops on my MAX-TST-DUO.
Might be worth trying?! You’ll need to use the appropriate domain names for your iPhone cell service if its different from the SIMs in the BR1.
Advanced > Settings > Service Pass through > IPSec NAT-T is disabled. This keeps the initial connection on Port 500 on the same route as the subsequent connection on Port 4500. I’ve found this is an essential if I want to route wifi calls over SpeedFusion tunnels (thank you to @C_Metz on WiFi Calling Priority )
Set up your SpeedFusion tunells and let them establish.
Then set up rules for the 2 (as far as I know) Verizon wifi calling domains:
I also have rules for domains to cover AT&T:
If anyone knows of other Verizon or AT&T related domains please let me know.
Hope that helps
David