The fine reputation of the company you work for
The great service or product you are selling
The reasonable price for the product or service
Your personality, your style, yourself
Calling around to find the best price
Calling the customer after the sale
Telephoning an upset customer
Make an unsolicited visit or telephone call to (someone), in an attempt to sell goods or services.
Find out if their credit is good
Find out if they are who they say they are
Find out what they want
Find out what they need and what they can afford
A better deal
Here's an interesting quiz for you.