We at Ground Control define CIR as a segment of your connection that is not shared with others on our satellite network, so transfer speeds are available and guaranteed 100% of the time. In addition, we will prioritize traffic such as VoIP phone service and other specialty applications to only use that CIR channel for the highest performance possible. Since a 1:1 CIR channel is not shared, it is typically more expensive than a shared service.
Some satellite providers use the term CIR loosely in describing shared plans, however, if a channel is shared, then obviously full speed can not be guaranteed 100% of the time.
Many of our customers use a small 20 x 20Kbps CIR for their VoIP phone connection so that conversations never drop off, no matter the load they place on the satellite network. This is because the VoIP line has a channel separate from the shared network.