Which IP telephony component provides call processing, such as signaling, that in a traditional voice network is provided by switching equipment, such as a PBX?

A.
Advanced call-handling software, such as Cisco Unity

B.
Call-management hardware and software, such as Cisco CallManager

C.
Client-based software, such as CiscoSoftPhone

D.
Voice gateways, such as the Cisco VG248 Analog Phone Gateway