Service providers are challenged with providing quality voice services to a fickle market that is increasingly demanding premium voice and data products and services. Proactive call detail analysis plays a key role in how service providers and in-house IT departments combat common voice quality issues.

This blog discusses how service providers can improve their VoIP service offerings by eliminating common voice-related problems by implementing call detail analysis on their VoIP solutions.

VoIP is highly sensitive to network performance variations since IP calls travel over the same media as data packets and break out over the Internet, where it needs to contend with other protocols for bandwidth. Companies that are courting a migration to VoIP from PSTN should take into consideration the reliability and quality of their data networks before adding voice services to their data networks.

Here are some VoIP factors that call detail analysis may reveal:

  1. Jitter and delay: Jitter commonly occurs on packet switched networks due to the fact that voice data is divided into smaller packets for outing over the network. These packets may take different routes over networks and arrive at their destination in non-sequential order. This is what causes poor quality in voice calls and causes audio to be scrambled.

Jitter buffer is a way of managing issues caused by jitter and packet delay-related quality issues. It temporarily holds voice packets in a buffer and allows for the reorganisation of packets in sequential order, which eliminates issues caused by packets arriving non-sequentially.

  1. Packet-loss: Common causes for packet-loss are high CPU usage in routers, competition for bandwidth from other network dependent applications or buffer overflows. Packet-loss is also a common occurrence in low-speed networks that are not well equipped to cater for the extra demands placed on it by VoIP traffic.

Packet Loss Concealment (PLC) is a technique that masks the effects of packet loss in VoIP communications by masking the loss of voice packets. This technique is only effective in low packet-loss scenarios and will not be able to cope in environments with unreliable infrastructure or low speed networks.

  1. Echo: Echo is when the caller hears his or her own voice a few milliseconds after speaking. This is primarily caused by a delay in the transmission of voice packets, which in turn is caused by congestion on the network. Extreme cases of echo usually result in callers dropping the phone call due to communication becoming practically impossible.

Echo cancellation devices (ECD) can be installed on voice gateways that examine and compare the outgoing and incoming signals for consistency in the data patterns. Once an inconsistency is determined, the ECD attenuates the effects caused by echo on the call, thereby reducing the effects caused by echoing.

How call detail analysis aids in overcoming voice quality problems.

Call Detail Records (CDR) are data records that contain information pertaining to originating and destination phone numbers, call start and end times, duration and other data that aids in accurate billing and other functions. Call Monitor Records (CMR) are the records that contain information about call quality metrics such as call status, addresses, packet count and packet loss statistics, current jitter and various other metrics that aid in identifying causes of poor VoIP call quality. 

To achieve consistent voice quality on your VoIP solution, you need to invest in monitoring tools that leverage the data found in both CDR and CMR data packets. These packets can be collected for analysis by Network Management Systems (NMS) that support monitoring and reporting on both data and voice packets travelling through your network. IRIS’ SD-Reporter is one such monitoring and analysis tool that provides network engineers and service providers with the tools they need to keep their voice solutions running optimally.

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