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mfitzgerald
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Joined: June 14 2006
Location: United States
Posts: 142
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| Posted: January 29 2007 at 2:51pm | IP Logged
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Not truly an issue, but an odd situation. I guess I’m posting this for my own validation.
The problem has been resolved, so all I want is to see if my assumption is correct.
The application I was working on was placed in an odd scenario where an incoming call would be answered automatically, and (due to a “quick-fix” for a completely different issue) would re-answer that call.
The call would be answered, however it would go on hold right away, even though I never sent a request for go on hold.
My assumption is that if two attempts to answer a single incoming INVITE are initiated, LS will assume the second as a request to go on hold.
Is this correct?
Just curious.
Thanks
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support
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Joined: January 26 2005
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Posts: 1666
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| Posted: January 30 2007 at 8:50am | IP Logged
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Hi Fitz,
<<< You
The problem has been resolved, so all I want is to see if my assumption is correct.
Support >>>
Do you mean this post?
Phone Call itself problem:
http://www.lanscapecorp.com/forum/forum_posts.asp?TID=249&TP N=1
<<< You
My assumption is that if two attempts to answer a single incoming INVITE are initiated, LS will assume the second as a request to go on hold.
Is this correct?
Support >>>
Not sure. We would have to see the SIP log that causes this situation. If it’s a possible bug, then we would like to fix it. If a call is answered quickly 2x or more at the same time, it may be possible that an internal state race condition exists- but that’s only a guess.
When an INVITE is received by the media engine, it will process it, generate certain 1xx provisional responses and then somewhere along the way, give the app the indication that the incoming call can be answered (SipOkToAnswerCall). The app should not try to answer the incoming call until the SipOkToAnswerCall event. The app should also call the GoOffHook() API procedure only once to answer an incoming call.
The media engine should also handle multiple INVITES being received OK for the same call so that should not be the problem.
It sounds as though your app answered an incoming call and then answered another incoming call immediately after. That situation would automatically place the first call on hold if the media engine was started using the “line mode” specified as PHONE_LINE. See the LineMode structure member of the START_SIP_TELEPHONY_PARAMS structure for more info.
If you want, feel free to post a SIP log of the situation.
Support
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mfitzgerald
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Joined: June 14 2006
Location: United States
Posts: 142
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| Posted: January 30 2007 at 12:05pm | IP Logged
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Initially the issue derived from an odd state resulting in that issue (Phone Call itself problem)
http://www.lanscapecorp.com/forum/forum_posts.asp?TID=249&TP N=1
(As a result of the problem mentioned in the above thread, we now run two programs, each on a different machine. It waists a perfectly good computer, but you have to do what you have to do.)
I’ll make this quick:
The application can run in one of two modes, auto-call, and auto-answer. The applications work together to keep a call active between each other on the PBX. Validation code is placed where the answering phone ignores all extensions (via a 480) other than the calling application. The calling application would ignore ALL incoming invite requests (via a 480). The validation and answering code was triggered in both cases in SipOkToAnswerCall event.
During testing--on rare occasions—the calling application could be caught up elsewhere and would not correctly send 480. This would never allow the phone to place an outgoing call to the answering application and so the phone would just keep ringing.
The “quick-fix” was to place the validation and 480 function call on the Sip Event SipStartIncomingRing. Oops, bad assumption.
This is what caused the quick/double answer of the single invite request in the answering application.
This case was very rare, and the “quick-fix” was re-fixed. It would not be wise to recode the application to replicate this so I apologize I do not have any SIP logs to show.
However as described previously, the answering application would answer the authorized calling application on the SipOkToAnswerCall event, which would trigger the SipStartIncomingRing event. In both cases because the validation code was the same and the incoming call was the valid extension, the call would be answered, re-answered and subsequently placed on hold. (Not an issue as no one is actually on the phone, thus an on-hold doesn’t matter) however, I was confused as no request to place the phone on hold was ever made.
It only took a little looking to see the error in logic. However as per your description it would appear that LS performed perfectly.
However it also seemed to have assumed that the second answer was actually answering another call (even though only one phone line was activated). And because the phone was already on a call, it would need to place that call on hold while it answered… well… the same call.
Thank you for your prompt reply. Your explanation has assisted in understanding this “quirk” and possibly any future scenarios like this.
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support
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Joined: January 26 2005
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| Posted: January 30 2007 at 3:19pm | IP Logged
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Hi Fitz,
Thanks for the good explanation. Our heads are kind of spinning though as we followed through the logic… :)
We are glad that you take the time to explain what you see with your VOIP app(s). Some customers do not do as well when they post issue reports to this forum and then we are left guessing what may be the issue/problem. Good show.
Continue to post as required. Once again, we regret the longer than usual delay with our latest responses. It has been very busy here since the start of the “new year.” This should subside.
Can we assume this support thread and the original “Phone Call itself problem” is resolved?
Support
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mfitzgerald
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Location: United States
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| Posted: January 30 2007 at 5:00pm | IP Logged
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To answer your question. No, the “Phone Call itself problem” remains an issue. The solution we have worked out is not ideal. It waists a completely capable computer that otherwise could be used to take care of our customers.
This thread was started only as a curiosity regarding an unexpected outcome.
Concerning the “Phone Call itself problem”.
We would like to use the multi-phone application as a multi-line-phone. It was required to do what the two applications above do, in a single application on a single system. (Trust me there is a reason for this, its just rather complicated to describe).
It still baffles me why LS seems to make the distinction of it calling its self vs. a 3rd party phone calling it with the same parameters. In addition there may be other issues down the road that would require this type of scenario.
We await word on the “Phone Call itself problem”
Thank you.
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support
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| Posted: January 31 2007 at 7:42am | IP Logged
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Hi Fitz,
Ok. We will get you the answer for the “Phone Call itself problem”.
Support
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mfitzgerald
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| Posted: January 31 2007 at 11:02am | IP Logged
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Thanks.
We await your response.
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support
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| Posted: February 13 2007 at 7:33pm | IP Logged
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Hi Fitz,
Sorry for the delay thus far. We are working other support issues that are zapping all of our time. We will be getting you an answer for this issue so please bear with us as we locate some time to investigate. It sucks to have to wait as long as you have but until we can “staff up”, there isn’t much choice. We have not forgotten about this post.
Support
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LanScape Support Forum -> LanScape VOIP Media Engine™ - Technical Support
Topic: Re-Answer Question
