Part of what got me started was a bad microphone on my phone, but I realized it had advantages when you're alone. Honestly, talking on the phone in public at all isn't great. Everyone can hear your side of the conversation, and while it's much better than eating pizza, people ought to avoid calls in public whenever possible. Whenever I'm around others, I keep the calls short, and when I'm alone and do take longer calls, I eat that pizza. Judge pizza eaters when you see them, but don't feel shame for doing it when alone. While you're at it, don't let people having loud, vibrant phone conversations off the hook.