ShoreTel Dropped Calls – Some fixes

This is quick post today. Recently we fixed a dropped call problem around here. I’d like to outline what actually caused the problem and how it was resolved.


I believe the initial cause was that I had upgraded to ShoreTel 12.1. If you take a look at you’ll see that they have a LOT of posts on how buggy this release was. The second problem we had only aggravated the first. We were having a lot of buggy faxes coming in and jittery phone calls.


ShoreTel support was pretty good at being able to figure out the problem, but had I noticed something I could have fixed it myself months ago.
First off, upgrade to 12.2. This will fix a lot of the dropped calls almost instantly.
As for the bad call quality. Our problem was simply that if you set your ports on your network switch to manually go to 100/Full Duplex the ShoreTel switch will guess that you really want “100/Half Duplex” which will lead to massive packet loss on heavy traffic days.
So all you need to do is console into the ShoreTel switch and make sure that the port is set to “100/Full Duplex”.
If you need instructions on how to do this, the “Quick Install Guide” provided with most switches and online at If you go through the configuration menu for network settings you’ll be given the option to set the port to whatever you need.
I recommend against setting these to Auto unless you’re using Netgear switches on the network. Cisco switches and ShoreTel switches don’t particularly play nice together.

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