In my experience, reference checking is one of the best ways to determine a good fit for a potential employee or vendor. Unfortunately, when I have been asked to provide references as a potential employee or vendor, few have followed up to talk with the reference. Of the references who were interviewed, the conversations tended to be short. In some cases, the reference checker might have already made their decision and is just going through the motions. In other cases, the reference checker might be inexperienced at asking great questions.
I recommend asking the reference to schedule 15-30 minutes for the meeting. If this decision is key to your business, an in-person interview is best and video call is second best. If your reference calls are less than 10 minutes, I don't believe you are asking enough questions. I recommend asking the same question in different ways. Typically I ask a positive question first, followed up by a negative version of the same question. I have received great insights by asking the person to stack rack the individual or company against their peers. In interviews, I ask candidates the name of their supervisor at each job and what their supervisor will say about them when I call their former supervisor. By asking follow up questions you are more likely to get to how they really feel.
I recommend starting the interview with some background on your potential project or job. This will help the reference get some context for your conversation and build some rapport.
Below are the sample interview questions I provided to a friend looking to hire a software development firm.
Can you tell me a little more about your project?
Did you evaluate other vendors before picking this vendor? If so, who?
How long did it take to complete?
What was your total budget?
Did the firm use a project management tool to track user stories, sprints and issues?
What did you like about working with this firm? You may want to drill down on specifics such as business analysis, project management, UX, testing, training, resolution of bugs
Where could this firm improve?
Did you complete the project on time?
Did you complete the project on budget?
Have you ever worked with other software development firms?
Who is the best development firm you have ever worked with?
Is there any advice you would provide to us to ensure we have a successful assuming we are going forward with working with this vendor?
Asking similar questions will help you succeed in hiring great vendors and employees. For more on the seven levels of why see this blog article. If you want to learn more about how to hire great employees, see the book referenced in this blog article.