Asterisk as Instanting Messaging/VoIP platform?

Hi,

Can Asterisk be used to build a carrier grade IM/VoIP platform based on the capabilities of SIP/RTP? When I say carrier grade, I mean, in the same league as Skype, GoogleTalk etc. Has anyone attempted this?

As far as I can tell, Asterisk is quite a scalable system, but is really meant to replace corporate PBX systems and requires an IT admin team to maintain.

Any feedback would be appreciated.

Thank you,

Paul

Cross-reference:

forums.digium.com/viewtopic.php?t=1755

Best not to double post.