When troubleshooting UCaaS quality of service, getting access to a packet capture (or PCAP) for a problem call is always the first step. Examining a packet capture with an analyzer such as Wireshark, is generally the only way to see what’s on the wire and verify that things are behaving as designed.
With voice quality issues, where you get the capture from is critical. Just like traffic on a highway, congestion in a VoIP network can happen at any point along a route, and your vantage point when looking at it is critical to understanding what is going on.
A key benefit that SkySwitch offers to white label resellers is access to RTP-Sight, a network monitoring tool that provides packet captures and analytics for every call, and dramatically improves the troubleshooting process. A limitation of RTP-Sight has been that packet captures are taken from the switch perspective, and can only tell half the story. Packets sent from the switch to a SIP endpoint may be delayed en route, and this would not be visible in the switch-side packet capture. In order to see what is truly going on, it is often necessary to get a packet capture from the end-customer site and then compare the two. Often, this is the only way to see trouble introduced downstream from the switch (such in the last mile or on the customer’s local network).
However, getting a packet capture from the end-customer’s site is sometimes not a viable option because the UCaaS provider lacks access to the end-customer’s network, or does not have equipment with packet capturing capability. And even if packet captures are available, encrypted RTP streams will preclude analysis.
SkySwitch now offers white label resellers another way to see what happened on the remote side of a call with the availability of RTCP and RTCP-XR statistics in RTP-Sight. RTCP is a protocol that allows supported SIP phones to provide feedback on the quality of service from the perspective of the remote endpoint. This is accomplished by configuring supported SIP endpoints to stream RTCP statistics to the RTP-Sight collector. These statistics include information such as transmitted packet counts, packet loss, packet delay variation, round-trip delay time and MOS. Access to such performance data for each IP phone makes it easier to diagnose problems remotely. And because RTCP is sent in a separate stream from RTP, encrypting RTP packets does not obscure this data.
The chart below shows a sample RTCP report displaying aggregate RTCP statistics over a 24-hour period.
Per call RTCP reports are also available as part of each Call Detail Record. The table below shows the RTCP statistics received from a SIP phone with IP address xx.xx.60.19, telling us the jitter and loss experienced by that endpoint on the RTP stream received from 75.98,50.46.
SkySwitch currently collects RTCP and RTCP-XR reports from Yealink, Vtech and Polycom SIP endpoints.