Has she contacted Verizon to discuss her issues? I had similar issues years ago and, after I complained, I believe Verizon took some action in their infrastructure (possibly adjusted the radiation pattern on their cell towers) which improved performance. Also, not all cell phones are equal in their sensitivity and signal processing. Ask Verizon if they'll let her test drive a different phone. And when I was having these issues, I also looked into the Verizon-supplied cell booster, and IIRC it required an internet connection only for handshaking to initiate the call, not for the ongoing call signal exchange, which was handled as a normal cell call through the towers. Since that time I've relied on the wifi calling feature and haven't had issues.