GoS - technical definition

In the PSTN or with respect to a PBX, the probability of a call being blocked or queued for some period of time due to limited system resources during the busy hour of the day. GoS is expressed as a decimal fraction. For example, P.03 indicates that there is a probability (P) that three (3) in every one hundred (100) call attempts will encounter a blockage condition (i.e., will fail to gain access to the system) during the busy hour of the day. See also traffic and traffic engineering.
In a packet network, a generic priority or similar preference given to a user, a location, or a type of traffic.

See GoS in Computer