Forum Discussion
Calls dropping and incoming callers hearing "All circuits are busy" messages
Since yesterday, we've been having issues with calls dropping, both within our network and to/from the PSTN. I've been making periodic test calls to myself this morning from my cell phone and about 50% of the time, I'm hearing a message saying "All circuits are busy".
Anyone else having trouble?
In case anyone is interested in the post-mortem, the call dropping issue turned out to be a very strange issue with our network.
I ran the https://www.microsoft.com/en-us/download/details.aspx?id=53885 (configured to perform 50 consecutive test calls) on our corporate network as well as the consumer-grade internet connection in our remote office testlab and compared the results. When run on our corporate network, 10% of the test calls had packet loss of 60% or greater, and all but one of the rest had packet loss of <1%. Packet loss on the testlab network was zero.
Our standby firewall appliance had recently started producing erroneous environmental sensor readings but otherwise seemed to be fully functional. Grasping at straws at this point, our network admin powered off that appliance and the packet loss disappeared. We're still not sure whether the root cause was software, hardware or perhaps even electrical interference.
The "All circuits are busy" issue turned out to be incidental to the call dropping issue. I can't say whether it was on the caller's side or Microsoft's.
2 Replies
In case anyone is interested in the post-mortem, the call dropping issue turned out to be a very strange issue with our network.
I ran the https://www.microsoft.com/en-us/download/details.aspx?id=53885 (configured to perform 50 consecutive test calls) on our corporate network as well as the consumer-grade internet connection in our remote office testlab and compared the results. When run on our corporate network, 10% of the test calls had packet loss of 60% or greater, and all but one of the rest had packet loss of <1%. Packet loss on the testlab network was zero.
Our standby firewall appliance had recently started producing erroneous environmental sensor readings but otherwise seemed to be fully functional. Grasping at straws at this point, our network admin powered off that appliance and the packet loss disappeared. We're still not sure whether the root cause was software, hardware or perhaps even electrical interference.
The "All circuits are busy" issue turned out to be incidental to the call dropping issue. I can't say whether it was on the caller's side or Microsoft's.
Just to clarify, the calls "within our network" that are dropping are all calls between sites where the clients don't have a direct route. Calls where clients can communicate directly don't seem to be dropping.
I'll also mention that everyone but me is in Islands or Skype for Business Only mode (so using Skype for Business Online), but I'm in Teams-Only mode and am having the same issues so I figured it would be best to post in the Teams community.