I love my iPhone. It's my primary means of digital communication over email, Slack, Trello, Facebook, Twitter and so forth. It's how I watch sports through the MLB and NFL apps. I meditate with it thanks to Headspace, check my banking with Mint, and book flights with Westjet.
But what I don't do, is use my phone for notes at meetings with clients.
What you need to be mindful of when meeting a client or prospective one is the absolutely appearance of active listening. Imagine if you were on a date - the moment either of you grabs the phone the chemistry is over. Why wouldn't it be the same at a meeting?
That's why a physical notebook is important. You can affirm the client's words and say, "let me record that on my notebook!" and they'll view it as the highest level of caring and attention to detail.
Trust me. Put down the phone, pick up the pen and jot down notes (even if it's just scribbles).