Ringless VoiceMail

I'm looking for a technical person who has good telecom experience and can help us develop ringless voicemail features. There are very few companies are doing this and we have no idea how do they do that.

Here is detail about one company that provides ringless VM :

[url removed, login to view]

You can read about it and tell me if you can do it.

We would ideally prefer some open source technologies to be used with it like FreeSwitch etc.

Please bid only if you know about and are able to help.

Thanks

Desired Skills

Freeswitch

Skills: FreeSwitch, VoIP