Dropped calls and wifi calling

Recently switched to Verizon and have had constant dropped calls when calling from home. Recently found out that my neighbor has to leave his house to make a call, again Verizon. Turning on Wi-Fi calling did nothing. A tip without an explanation was to turn on Airplane Mode along with Wi-Fi calling. That has worked perfectly. Do not understand why Wi-Fi calling by itself did not work. My phone is a 13Pro and twice has had a diagnostic check. My girlfriend has a 12 Mini, with Verizon, and can make and receive calls anywhere in the house. She does have Wi-Fi calling turned on and Airplane mode turned off.