... intelligent IP telephony design and implementation has a critical reliance on VoIPsignaling protocols.Chris Olsen, Global Knowledge Instructor, CCSI, CCNA, CCNP, CCVPUnderstanding Voice over IP Signaling ... Cisco VoIP installation. Also important tonote is that all of these protocols are based on IP, thus, requiring an existing IP infrastructure to operate. Anyerror in IP or relating to IP, such ... on one IP phone calls another IP phone, which is not present, and the call goes to voice mail (or an IVR system). As the user is hearing the voice mail prompt as well as leaving the audio voice mail,...