Segment Spotlight: Pinpointing the Source of Call Quality Issues

Author: Lars Nohling, Sr. Systems Engineer at Edgewater Networks

Mavenir_BlogAs everyone knows, call quality issues can seriously hinder corporate productivity. There isn’t a single person in corporate America that hasn’t been on a call or conference bridge that had to be terminated or interrupted because there was too much static, jitter and/or echo to effectively communicate.  And, we’ve all tried to place calls and found that no dial tone was available.

As those responsible for managing these solutions know, call quality issues can originate from many sources. Let’s take a closer look at a few in particular.

Traffic not properly prioritized
Unlike data solutions, VoIP solutions are uniquely vulnerable to service disruption during traffic spikes – an issue that manifests as jitter, echo, etc.  These problems become persistent when traffic is not properly prioritized.  Many times, Class of Service or Multi-protocol Label Switching settings that enable policy-based network management are improperly copied when systems are expanded, upgraded or migrated to next-gen hardware.

Codec incompatibility
When endpoints are not set to use the same codecs (G.711, G.722, etc.) as the VoIP infrastructure, a variety of issues can occur including poor voice quality, dropped calls and an inability to place calls outside of the organization.

Variations in carrier service
Clearly, fluctuations in availability from the service provider will have a direct impact on the corporate phone systems they empower.  Because carriers use complex redundancy schemes to overcome local outages, those issues that do end up impacting end-users tend to be extremely complex and hard to diagnose on their end.  Without empirical evidence, often times carriers will deny responsibility, forcing IT to hunt for other causes.

LAN/WAN connectivity problems
Any breakdown in the IT infrastructure that impacts the network’s ability to seamlessly transmit VoIP traffic will create problems that users will experience as jitter, echo and latency on the call.

Call routing inconsistencies
Keeping call routing tables accurate in the face of constant organizational change can be extremely difficult.  It becomes even more complicated as companies strive to use complex schemes to better match agent/support resources with customer needs.  Routing issues create disconnects between callers and their intended parties.

To accurately troubleshoot, companies need to understand if an issue is related to a specific piece of equipment, carrier deficiency, or provisioning error or if it is part of a larger problem where usage exceeds infrastructure capacity. Enterprise session border controllers (ESBCs) are critical to rapidly diagnosing issues as they allow companies to see the whole picture. By monitoring VoIP traffic and call quality at the customer edge they can help determine at what point service is breaking down.  And they can use MOS scores –a numerical rating of the quality of human speech at the endpoint – to accurately assess performance from the user perspective.

More sophisticated solutions offer traffic shaping features for determining if the network itself is properly prioritizing voice traffic and discover when voice packets are being lost or delayed as systems become overloaded.

ESBCs are especially important for companies that are using OTT, hosted or managed VoIP and PBX services. Without any insight into voice quality and performance metrics, IT groups would be forced to rely on user complaints to assess service delivery. Clearly, this approach to pinpoint issues is less than ideal.

Proactively assessing VoIP system performance from end to end is the best way to preempt call quality issues and keep users from experiencing problems as they go about their business.



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