Verizon iPhones - No WifFi Calling on Cisco Network

Has anyone on a Cisco wireless network recently started to experience WiFi Calling issues with iPhones from Verizon?

Cisco 8540 WLCs running code
All Verizon iPhones running 13.3.1


We aren’t running that setup here, but from the Cisco docs, it appears they tested on i(Phone)OS 13.2.1, so this could be something introduced by the iOS update. It appears it is not uncommon for WiFi calling to break following iOS updates.

It is possible that clearing some VZN network settings may help, as recommended in this article: