Panasonic KX-NCP500/1000 Telecommunications Platform - takes up at least 2U of rack space

This platform is for setting up your VoIP network. It has the ability to be upgraded and works with all sorts of VoIP communications devices. It even has integrated desktop and network applications.

You can use it for messaging and mobile devices as well. The system works with all sorts of SIP devices, IP-based telephones, DECT phones, IP soft phones or you can even set it up to work with standard analog telephones.

I don't know why you'd waste a system like this with old-school analog phones, but I could see the cost savings of implementing VoIP at core immediately and then slowly phasing out the old analog devices. Again, I have no clue on price, but if you have to ask, you probably can't afford it as networking equipment of this caliber is generally not cheap, but its probably available whenever you cut the check.