Class Of Service (CoS), when utilized within a MPLS (multiprotocol label switching) network, facilitates packet prioritization so that multiple applications, such as voice, video conferencing and routine data can be effectively transferred over one bandwidth pipe. This relatively new technology enables great cost savings and increased efficiency for businesses which in the past have needed to use multiple smaller bandwidth channels to effectively implement each application separately. With CoS, each data packet is provided a priority designation, so that as packets for more important, or latency/packet loss sensitive applications, like VoIP receive highest priority as they move through a network. CoS also ensures that more routine applications such as email, receive lower priority so that they do not compete for finite bandwidth resources. Many industry insiders use the terms CoS and QoS (Quality of Service) interchangeably. However, these two terms carry two different meanings. QoS refers to performance/efficiency standards related to bandwidth circuits, whereas, CoS refers to packet prioritization within the circuit.
VoIP (voice over internet protocol) voice traffic can be transmitted over the public internet, across the secure network of a telecom provider, or via the private MPLS network of a multi-location business. VoIP over the internet has its limitations because CoS (Class of Service) packet prioritization cannot be enforced on the public internet. The result of this is that voice traffic is competing with all other internet traffic at each relay. This lack of CoS can often result in latency and packet loss. High latency and packet loss often results in poor voice quality. These issues are virtually non-existent with VoIP over private network telecom provider. With this option, the provider keeps all voice traffic on their private network, until this traffic reaches the PSTN (Public Switched Telephone Network). This allows the provider to ensure that voice traffic receives top priority at each network relay, and more routine, less latency sensitive applications receive lower priority, while a call is in progress. The result of these measures is virtually perfect call quality. All major telecom providers now routinely utilize VoIP technology voice transmission. With VoIP over the private MPLS (Multiprotocol label switching) network of a multi-location business, CoS is ensured by the provider, so call quality is excellent in these situations as well. An advantage for businesses with VoIP over an MPLS network is that all location-to-location calls within this network are free.