I found the solution, and I'll explain it.
I did all the steps in the link given in the link at comment #4.
Since my carrier (Bell) isn't it the list, I've tried those provided, one by one, until I found one that worked.
+QMBNCFG: "List",2,0,0,"hVoLTE-Verizon",0x05010141,202004091
I hope it will help people who are trying to enable voLTE calls with Bell.
I did all the steps in the link given in the link at comment #4.
Since my carrier (Bell) isn't it the list, I've tried those provided, one by one, until I found one that worked.
+QMBNCFG: "List",2,0,0,"hVoLTE-Verizon",0x05010141,202004091
I hope it will help people who are trying to enable voLTE calls with Bell.