Coming from a sales background and currently working in IT I can say that Cold calling and closing are two VERY important skills in business. The power you have with just your voice is incredible.
Some people find it hard to convey their personality on the phone but it's absolutely possible. The best thing to do is go in with a script that is specifically developed to convert leads into clients.
You should always start with the professional side of things e.g.
Hey I'm Poly from X, I've been personally told to call you to tell you about Y.
Then expand your pitch from there. Make sure to look up human psychology when it comes to sales and incorporate it into your pitch. Keep it short and snappy to open with. Ensure you always control the call and never let the lead take over.
From here you should try to be indifferent. Get friendly with the lead, use your "banter" but do not use anything that may be offensive. Personal connection is the number 1 way that you get clients to trust you along with a great product/service and pitch.
Here's an example of how to take control:
Sorry I don't have time right now
That's okay I understand you're busy, Let me leave you with this question.
(starting a conversation and understanding what your call needs, use this response to gauge what type of person the call is.
Not letting negatives end your potential sale is VERY important when making sales. 95% of sales made do not come from the first call nor do they come without resistance, the 5% that do are really luck of the draw.