TW, why would you expect them to call you back? If they contacted you once, then it is YOUR responsibility to keep trying until you get through to them. You're putting your prospects on the spot. They're afraid that, by calling you back, you'll assume they want something they may not once they have more info. Safer not to call or respond than to be badgered by someone who may or may not be you. It's fear, plain and simple. I'm assuming you're using a toll free number, right? If not, they may be afraid it's one of those routed to the moon, the Caribbean, or some place that's going to cost them a few thousand to call.

You might examine the content of your message/request and see if it strikes people wrong in some way. Test it out on friends, family, even strangers you meet...but test it. It may be in the way it is worded or sounds to them...not the way you mean it, even. Something is wrong, that's for sure...so test, test, test! BTW: have the testers READ the message, as your recipients would, so your voice inflections don't influence their perception of the message.

One other thing: do you have enough lines and operators so they don't get busy signals constantly? You could have call waiting to test this out or just put them through to a voice mailbox asking that they tell you a time/date (as applicable) to call them back in addition to the usual.

Have you offered an incentive for them to call you? People love to be rewarded.

Good luck!

Sandi Bowman