Grade of service may be viewed independently from the perspective of incoming versus outgoing calls, and is not necessarily equal in each direction or between different source-destination pairs.
Criteria for mobile quality of service in cellular telephone circuits include the probability of abnormal termination of the call.
[1] The Grade of Service is one aspect of the quality a customer can expect to experience when making a telephone call.
[2] In a Loss System, the Grade of Service is described as that proportion of calls that are lost due to congestion in the busy hour.
The grade of service is a measure of the ability of a user to access a trunk system during the busiest hour.
To achieve and maintain a given Grade of Service, the operator must ensure that sufficient telecommunications circuits or routes are available to meet a specific level of demand.
It should also be kept in mind that too many circuits will create a situation where the operator is providing excess capacity which may never be used, or at the very least may be severely underutilized.
To determine the correct number of circuits that are required, telecommunications service providers make use of Traffic Tables.
This equation allows operators to determine whether each of their circuit groups meet the required Grade of Service, simply by monitoring the reference traffic intensity.