Every leg of a call that made to or from the UCX uses bandwidth in both directions during the call while it is on the IP network. By default, the UCX uses G.711 encoding of the voice which requires approximately 100 kb/s of bandwidth per direction.
So the total bandwidth required for UCX IP calls will vary based on your network topology and the number of simultaneous calls your business will require. But remember that there are other services such as web browsing, streaming services, email and other corporate data usages that require the bandwidth as well, so it is important to assess the overall bandwidth requirements. E-MetroTel recommends planning for an 80%
Latency is a measure of the time it takes for (voice) packets to reach the far end of a connection. For voice calls the higher the latency, the more difficult it is to communicate effectively over the connection, and may even cause calls to drop. E-MetroTel recommends that the end to end latency across a WAN connection to another site or to a UCX Cloud server less than 100 ms.
Jitter is the amount of variation in the time it takes for packets to arrive at their destination, i.e. the inconsistency of the latency. Too much jitter can cause significant call quality issues. E-MetroTel recommends jitter be less than in the 20-30 ms range, and certainly never over 100 ms.
While some degree of packet loss is tolerable in a Voice over IP call, packet loss over 3% can begin to significantly degrade the call quality.
E-MetroTel does not recommend specific brands of routers. However, some of the router capabilities used to connect the office to the WAN need to be taken into consideration.
Many brands of routers offer some level of firewall capabilities that are intended to make intelligent decisions on which packets can pass from the WAN to the customer LAN. These capabilities attempt to determine where certain packets really should go once they are passed (or if they pass) through the firewall, and they don't necessarily make the correct choices. SIP ALGs will often result in one-way audio , no ringing, or dropped call.
E-MetroTel requires that SIP ALGs be turned off. For more information refer to Unexpected call failures and registration problems.
Many business class routers can be configured to prioritize certain packets over others as they pass from the high-bandwidth environment of the LAN to the narrower bandwidth WAN. In many cases this involves having the router look at a certain portion of the packets to determine if they have been marked with special Differentiated Services (DiffServ) codes. E-MetroTel marks VoIP related media packets with the Expedited Forwarding (EF) code by default, which is the industry standard. However, if your router requires some other value, refer to SIP Settings for an explanation of how this can be changed on the UCX.