Once you sign up, you give them your cell phone number and they intern give you a local number you can call so that you can send Voicemails to people in your Contacts. The people in your contacts can either be other Pingers or just people with Email. Importing my Gmail contacts was a snap. I just tell Pinger that I am going to use Gmail, sign in with my Gmail user and password and it synchs with my Gmail contacts either daily or manually. So, once everything is setup and verified, they verify with emails and text messages, you simply call the number they give you and say the name of the contact who you want to send a message to, confirm it, and away the message goes.
If the person is a Pinger, they will recieve a text message with a local number for them to call to hear the voicemail. There are no prompts whatsoever. The text message tells you who its from, and all you hear is the voicemail when you call, then you can delete it or reply after you hear it. Every new voicemail has its own phone number. Pretty slick. Once you delete that voicemail the number is no longer valid.
If the person you send the voicemail to is not a Pinger then they simply get an email with a link to hear the Voicemail. Gmail has its own Voicemail player, but it wont work with Pinger because they dont send it as an attachment. Still cool.
As a Pinger, you also get a cool Inbox Voicemail manager when you sign up. It uses a lot of Ajax so its pretty streamlined.
I highly recommened checking it out! and Ping me if you have my gmail.