To end the voicemail, state (or restate) your main question, then say your phone number. You can also say you’ll follow-up with an email. Now, this isn’t the same as saying, “If I don’t hear from you, you’ll hear from me!” Instead, it’s giving them another way to contact you, one they may be more comfortable with. They should still feel a responsibility to respond to your question, but now they have two options for how to get back in touch. (Then send that email, of course.)
This is a tactic we picked up from Jeff Hoffman and it works because it makes you more memorable and makes your messages seem genuine and less rehearsed. Give it a try and see if it will work for you too!

Perhaps the biggest mistake in a sales voicemail is pitching too aggressively. If you sound like a smarmy used car salesperson, your prospects are going to delete your voicemails faster than you can say "lowest price guaranteed!"
“Hello ____. This is _____ again, calling from ______. I ran across some information on a client who made dozens of offers on houses before someone finally accepted one of them. We learned a lot from the experienced and I successfully used the findings to help other homebuyers make bids that were accepted early in the house hunting process. I thought I would share it with you in hopes of saving you time and making it easier for you to purchase the home of your dreams. I’ll email you the information. Give me a call if you would like to review it together. Thank you.”