Slydial lets you leave a voice message in any US mobile user’s mailbox, without ringing their phone. This is sort of like texting, but by voice instead. Call Slydial’s number, hear an ad, enter the recipient’s number, and record your message. The recipient gets notified in the usual way, sees your CallerID, and hears your message. (There’s an ad-free version, too.)
Slydial may be useful for people who can’t text due to vision, speech, or dexterity impairments, but want to get in on the fabulous forestalling fashion of one-way communication. And some people are just shy.