Asterisk Voicemail for iPhone allows you to check your voicemail messages on your Asterisk phone system from your iPhone.

It works similar to the native iPhone Visual Voicemail, allowing you to list messages, listen to messages, display caller-id information, delete and move messages, return calls and change voicemail settings all from your iPhone.

The technology behind it is Asterisk , PHP for the backend, Smarty and iUI for the frontend. Asterisk is an open source PBX (Private Branch Exchange) that provides all the functionality of high-end business telephone systems, and much more. It is the world's most flexible and extensible telephone system, providing many features that are not yet available in even the most advanced proprietary systems. It is also the world's cheapest telephone system. The software is free and runs on inexpensive Linux servers. Here are a few reasons why you should try Asterisk in your environment:

1. It is open source!
2. It has a strong and loyal community that continues to grow. While there are many open source solutions, most don't have nearly the support that Asterisk has.
3. Its configuration files are so granular you can configure Asterisk to do just about anything and you can easily add third-party applications (weather reports, Bluetooth integration, …).
4. If a feature doesn't exist, or you need help with something, you can ask the Asterisk community.
5. Even Linux novices can try Asterisk with a simple bootable ISO image called AsteriskNOW.

The application and code is available on Google's Code division or you can check out the live demo.