Hi Levi,
Phone chatting with someone you met on a dating site before meeting up is a good idea.
You are right about the vibe thing.
Best to discover that while chatting on the phone than over a date that you have now expended time, money and effort on.
However, many people still prefer to meet without having a phone call.
Some are intimidated by the prospect of chatting on the phone first and believe that they are better conversationalists in person and others worry about the prospect of giving their phone number to a stranger that they just met on a dating site.
The most important factor is that it works for you and as long as it does, keep doing it.