Network Effectiveness Ratio (NER) measures a network’s ability to deliver a call to a destination device, terminal, or recipient. It captures the percentage of successful calls by comparing the number of completed calls vs. the total number of calls made over the network.

For people who are managing a call center or a business phone system, a high NER indicates that network service is reliable: Calls are completed without technical issues.

This is strictly a network quality measurement. If someone calls in and gets a busy signal or gets sent to voicemail, NER counts that as a successful call — the network successfully got the call to its final destination — but no call center manager would describe those outcomes as “successful.”

For call quality and customer experience, there is a lot that the NER won’t tell you. However, if NER starts to drop from its normal baseline, it’s worth testing your network to figure out what’s wrong.

How Network Effectiveness Ratio works

To measure the percentage of completed calls, NER looks at the total number of calls logged in the system compared to the total number of completed calls.

NER excludes calls that fail due to user-related errors from the total number of calls, which ensures that it remains an accurate indicator of network quality. If someone reaches a busy signal and hangs up, for example, it’s not a networking issue.

NER counts any call as complete if the network is able to hand off the call to the final destination, even if the call is not answered.

Calculating NER

To calculate NER, then, you have to measure all calls that the network successfully placed to its final destination, which includes:

• Answered calls.
• Unanswered calls.
• Busy signals.
• Terminal rejections.

While some of these outcomes are not good from a business perspective, callers getting a busy signal indicates that the network is working just fine.

If you have these metrics, along with the total number of calls logged by the system, you have everything you need to fill in the formula and calculate NER:

NER % = 100 x (Answered calls + User Busy + Ring no Answer + Terminal Reject Seizures)/Total Calls

Because of the way that NER counts completed calls, it is a very good indicator of network quality.

However, if you are responsible for different types of call center quality monitoring, there is another closely related metric that will be far more helpful.

NER vs ASR

Network Effectiveness Ratio should not be confused with another important measure of network quality known as the answer seizure ratio (ASR). This is a measurement of the total number of answered calls versus the total number of attempted calls (known as seizures).

Both NER and ASR are used to evaluate network quality, but they account for terminal and customer behavior differently.

Since ASR counts call rejections and busy signals as failures, its value is greatly affected by user action. For this reason, it’s also known as the call completion rate, as it only indicates your network quality based on total call volume and call success rates.

NER more accurately represents the true performance of a given network. It strictly focuses on the percentage of call failures that were the result of network problems — it’s not going to help you account for customer behavior.

This is why, despite being the most accurate metric for network performance, NER isn’t used in the industry as much as ASR, especially when evaluating VoIP phone service quality.

Calculating ASR

To calculate ASR, use this formula:

ASR % = 100 x (total number of answered calls / total number of calls)

The information you need to calculate these ratios can be found in call details records of your phone system, though many modern call center solutions will have ASR visible in a dashboard.

NER is not the most important call center metric

Businesses use several call center metrics to gauge quality of service and how well they are serving customer needs. Under normal circumstances, NER is not the most important metric. It isn’t going to tell you enough about the nature of the calls to make decisions about how to improve call flows, support agents, or whether customers are having difficulty.

For instance, the call abandonment rate tells you the average number or percentage of callers who hang up or give up on their calls before reaching an agent or resolving an issue. Network Effectiveness Ratio doesn’t capture this important issue — as far as NER is concerned, the call went fine.

So it’s important to consider NER within the context of other metrics, such as:

• First contact/call resolution (FCR): Since first impressions matter, call centers don’t want customers to make repeated calls or follow-ups because of how negatively it can affect their experience. Therefore, a high FCR rate reflects greater user satisfaction because it indicates that customers are getting their problems solved efficiently.
• Average call duration (ACD): This calculates the average length of time agents spend on a support call. Its duration positively correlates with NER, indicating good contact center connectivity. While call centers generally want to optimize their resolution speeds, they don’t want customers to feel like agents are brushing them off.
• Average speed of answer (ASA): ASA measures the time it takes for a contact center to respond to inbound calls. Customers prefer to have their calls answered quickly by an agent or representative.
• Customer satisfaction (CSAT): As its name implies, CSAT is used to evaluate customer satisfaction, which is typically measured through surveys that capture how users feel about their interactions with call center agents and the assistance they receive.
• Net Promoter Score (NPS): NPS measures customer and brand loyalty. It is typically administered quarterly or bi-quarterly via surveys regarding long-term satisfaction. NPS does this by categorizing customers with decreasing levels of engagement as promoters, passives, and detractors.
• Customer Effort Score (CES): The operative word in CES is effort because it represents process friction. CES judges how hard customers must try to resolve their issues or to reach an agent.

What to do if there’s an issue with NER

Any sort of sudden drop in NER is a warning sign that something is wrong with your network. If it persists, here are a few things you can do to figure out what’s going on.

Start by investigating Call Detail Records (CDRs) and look for trends. Are there common failure points that signal a specific technical issue? Is the problem universal, or is the problem isolated to a particular region, carrier, call route, etc.?

If there is no clear sign in the CDRs, use a network monitoring software to investigate your VoIP infrastructure. You may find an issue with your internal network, but it may be the case that you have to reach out to third-parties and check for outages.

If the network seems healthy but you are still experiencing declining NER, you may have to review basic settings like VoIP codecs, QOS, bandwidth allocation, and even network configuration.

If it isn’t already, consider running VoIP on a separate Virtual Local Area Network (VLAN). Setting up a VLAN for voice traffic is a standard best practice because it separates your voice traffic from everything else happening at the office, ensuring the steady connection VoIP requires.