SIP (Session Initiation Protocol) is a Protocol Standard established by the Internet Engineering Task Force (IETF) Organization to define the control of communication sessions, such as messaging, voice and video calls over the Internet. SIP Trunking is a term commonly used to define the use of "VoIP Channels" in a similar fashion as traditional Telephony Trunks; one SIP Trunk or channel allows for the setup of one phone call (inbound or outbound) at a time. Call Waiting, in contrast, notifies the called party that a second call is in progress; the called party in most cases is unable to answer the second call, thus preventing the Business from effectively communicate with its Customers. SIP Trunking offers the advantage that a second call can be "rolled over" to a second channel therefore ensuring that any calls from Customers are not missed.