I have a Pixel 9a phone and use ID sim card.  I have been having terrible problems with calls dropping in the middle of conversations.  My ID signal in the house is not good.  Im sitting right by the modem in the house when making calls.  My computer and TV are working fine on wifi.  So I dont know why it keeps trying to switch back to ID for the call?  I have an honest Sim but have turned that off for now (its DATA only so should not interfere with making calls I dont think??)  

The last thing I am trying is to switch on Airplane mode and then choose wifi manually.  I have not fully tested this.   But is this really necessary?  Is it that ID do not want me to use WiFi calling and somehow prevent me to permanently chose it for making calls?