A process of elimination will be needed. And I am assuming the affected phone has already been restarted without resolution.
Has your WiFi-calling worked in the past, and if so when? What may have changed in the intervening?
Does your WiFi-calling not work regardless of broadband router? Or are only some affected? Former might suggest a device/SIM issue.. latter would suggest router issue.
If only certain routers are affected, can your husband's phone use WiFi-calling on the same?
Although a SIM/account issue is unlikely, you can easily prove/disprove by a 2way SIM-swap.. (this assumes standard physical SIM and not electronic SIM)
Put your non-working SIM in your husband's working phone.. what result?
Put your husband's working SIM in your non-working phone.. what result?
