Our other brand pbx shows the ping times of all the extensions and trunks. This is extremely useful as a broad troubleshooting tool. All of our extensions are hosted and from different sites/connections.
For instance, if we see a group of extensions with higher than normal ping times, it's usually a problem with that customer's internet connection and we can save a lot of diagnostic time by having the end customer follow up with their ISP.
Same holds true for the trunks. While rare, if we start seeing high ping times with all of our trunk providers, then it's likely an issue at our data center. If it's only with one provider, it's likely on their end.
Sometimes we see high ping times on one or two extensions from the same connection. We have found that this is usually a customer network issue, bad cord, bad switch port, etc.
So ping times would be extremely useful as a "cut it in half" tool when troubleshooting phone issues.