Background
I've written a program that hits a database, gets a list of outstanding bookings that need to be confirmed by a supplier, and makes a phone call. It will call a supplier about a specific booking up to 4 times a day to try and get it confirmed. It runs every day from 8-5 and has been running fairly successfully for the last 8 months.
Problem
The problem is manifesting as a Microsoft.Rtc.Signaling.OperationTimeoutException. When it was first deployed to live, I saw that error very occasionally but it was never a huge problem because the program would call multiple times. If it didn't get through one time, it was bound to the next. But in the last several months, this error has happened much more frequently to the point that some bookings aren't being confirmed at all. In November, the error was logged about 60 times and in December it was logged 142 times.
Error
System.Exception: Error in TotBlaster -- see inner exception for details; Endpoint URI = sip:LyncWorkflowUser@*.com;opaque=user:epid:WNbBJ5glhVypnI5020QiBwAA;gruu ---> Microsoft.Rtc.Signaling.OperationTimeoutException: Call operation took more than
expected time to complete.
at Microsoft.Rtc.Signaling.SipAsyncResult`1.ThrowIfFailed()
at Microsoft.Rtc.Signaling.Helper.EndAsyncOperation[T](Object owner, IAsyncResult result)
at Microsoft.Rtc.Collaboration.Call.EndEstablishCore(IAsyncResult result)
at Blaster.TotBlaster.<InitializeAndBeginPhoneCall>b__3(IAsyncResult result)
--- End of inner exception stack trace ---
I've been able to gather some informational logs around when the error is occuring as well (editing out some internal details about the bookings):
Calling 'tel:**********'; Endpoint URI = sip:LyncWorkflowUser@*.com;opaque=user:epid:WNbBJ5glhVypnI5020QiBwAA;gruu
*** AudioVideoCall_StateChanged from Idle to Establishing ***; TransitionReason = Establishing;
*** AudioVideoCall_AudioVideoFlowConfigurationRequested ***;
*** AudioVideoFlow_StateChanged from Idle to Active ***;
*** AudioVideoCall_StateChanged from Establishing to Terminating ***; TransitionReason = EstablishFailed;
*** OnCallEstablishCompleted ***;
Issues
I've been trying for some time now, and I simply can not reproduce this error on my dev machine. The problem can't be related to credentials as calls are going through probably 70% of the time. If I had to guess, I would say the problem is in trying to connect to a phone line to dial out, but I can't even be sure of that. I've checked the forums and googled for hours, but am still no further along in dealing with this issue.
Is anyone able to give some insight as to what is happening?