What does ASR measure and what can it tell us?
ASR - An invaluable measure of voice network quality
ASR is an abbreviation of the term Answer Seizure Ratio, which is a measurement of network quality as defined by the International Telecommunications Union in recommendations SG2. The ASR of a network can be calculated by taking the figure of the total number of successfully answered calls, and then dividing this figure by the total number of calls that have been attempted (call seizures). For example, if 500,000 calls are made in one day through a network, and only 250,000 of these calls were successfully connected, the ASR would be 0.5. Below are some examples of what the ASR can tell us about a network, as well as the call traffic that runs over that network.
Customers are using bad data sources
It is extremely important to note that busy tones and other call rejections by the called number will also count as call failures, and as a result we shouldn't take the ASR as the sole indicator of network quality. For example, lets say that a couple of customers send a high volume of call traffic over a network on a daily basis, but this customer uses terrible data to make these calls through their diallers. The expectation here would be that the ASR will drop significantly because there will be a low volume if connected calls in comparison to the total calls that have been made by the broadcaster.
There isn't enough capacity to route the calls being made
As explained above, any call rejection - even one from a carrier will be counted as a call seizure. Therefore, if a network is seeing a very low ASR, and they have no customers that dial bad data (explained above), then it would be good practice to evaluate the capacity that is available on the network and compare that to the calls that are being attempted. If this evaluation shows that there isn't enough capacity to deliver the calls that are being made, then additional capacity would need to be provisioned in order to improve the ASR can be improved.
There is an issue with some network infrastructure
If checks have been completed to ensure that there are no customers that are using bad data, and that the network has ample capacity to deliver the calls that are being initiated, then a low ASR could indicate an issue with some part of the network such as a media gateway, or switch.
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