Tellabs' equipment was designed for an era of circuit switching.

FORBES: Survival technique: paranoia

Tellabs is good with one aspect of circuit switching.

FORBES: Survival technique: paranoia

They then analyze how the remaining major cost components, switching and transmission for both types of networks and interconnecting with the switched circuit network for the IP-based networks, change with the change in technology.

CNN: IP telephony is the "in" thing these days, but should it be?

At the carrier switching office, the voice is separated from the data and converted back to regular circuit-switched voice.

CNN: Voice over DSL trial passes muster

Their conclusion is that the switching and transmission costs for IP-based telephone networks are much lower than for switched circuit telephone networks.

CNN: IP telephony is the "in" thing these days, but should it be?