Network Effectiveness Ratio (NER) measures the network's ability to deliver a call to the called terminal. The busy signal and other errors caused by user behavior are considered as “successfully delivered calls” for calculating NER. Unlike ASR , NER excludes client and terminal equipment behavior. NER is considered a network quality meter by ITU-T recommendation.
The NER Index was proposed in addition to ITU Recommendation: E.411 . It is conceived in order to eliminate a factor that depends on the behavior of the end user and to obtain a more complete picture of the quality of the communication channel.
It is calculated as a percentage: (Answered calls + Number of calls when the subscriber was busy + Calls that were not answered + Calls rejected by the terminal equipment of the subscriber) / Total number of calls.