Once you've tried holding a few audio conferences, you should consider doing more.
Your organization could sponsor an entire series of audio teleconferences. This is just one more way to improve your industry profile, communicate with clients and customers and spread the word about what you do.
Conference calls are great idea generators. So if you have one you are certain to get ideas for the next one and the one after that from the discussion. You will hear about or come up with new projects, initiatives, and resources after you've had the opportunity to get into dialogue with others in your industry.
You can plan your series to go with a yearly calendar, academic calendar, or to follow some other pattern. You could schedule conferences on a quarterly basis or on some other plan that fits your industry.
As the plan gains momentum, you'll find that more people want to get on board. At the start you will likely have to do a lot of publicity. It will be up to you to get those phone lines jumping and to find speakers, within or outside of your organization. Eventually you will be able to book industry experts who are seeking to join your conferences.