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Calls crossing


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We have strange issue with one client running 3.0.1.3023 (Win32), they use Broadvox as their ITSP. several times maybe once or twice a day people who try calling in from Sprint cell phones do not reach the autoattendant, a total stranger picks up the phone and would not identify himself.

 

The call logs shows the call came in to the auto attendant, I don't see the call being forwarded elsewhere, in the log files.

 

Does it sound like someone hacking in to the system and intercepting calls?

 

I attached a log of 1 of these calls, I can't reproduce on demand however if I try enough times it happens, this just started over the last few weeks.

log.txt

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We have strange issue with one client running 3.0.1.3023 (Win32), they use Broadvox as their ITSP. several times maybe once or twice a day people who try calling in from Sprint cell phones do not reach the autoattendant, a total stranger picks up the phone and would not identify himself.

 

The call logs shows the call came in to the auto attendant, I don't see the call being forwarded elsewhere, in the log files.

 

Does it sound like someone hacking in to the system and intercepting calls?

 

I attached a log of 1 of these calls, I can't reproduce on demand however if I try enough times it happens, this just started over the last few weeks.

 

This is usually a sign that there is a port conflict with RTP. For some reason, two calls point to the same IP port. This might be caused by the router (if it is buggy) or maybe the carrier has a problem there (less probable I would say). Some routers have only 32 NAT entries, and if you have too many NAT bindings you may have an effect like this.

 

How to troubleshoot this? Difficult. If you have a cheap router, I would just try another router from another company and see if that changes anything.

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This is usually a sign that there is a port conflict with RTP. For some reason, two calls point to the same IP port. This might be caused by the router (if it is buggy) or maybe the carrier has a problem there (less probable I would say). Some routers have only 32 NAT entries, and if you have too many NAT bindings you may have an effect like this.

 

How to troubleshoot this? Difficult. If you have a cheap router, I would just try another router from another company and see if that changes anything.

 

They have an enterprise class router, there is no NAT involved, most complaints of this problem have been after business hours, workers calling in to check their voice mail, there were no other active calls on the server at the same time.

 

I had it a few times myself when I called in, it seems to forward to the same person usually, I once got someone's voicemail, however it disconnected before I was able to hear their complete phone number. It may be a coincidence that every one who complained about this problem was using Sprint cell phones.

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They have an enterprise class router, there is no NAT involved, most complaints of this problem have been after business hours, workers calling in to check their voice mail, there were no other active calls on the server at the same time.

 

I had it a few times myself when I called in, it seems to forward to the same person usually, I once got someone's voicemail, however it disconnected before I was able to hear their complete phone number. It may be a coincidence that every one who complained about this problem was using Sprint cell phones.

 

Whow maybe Sprint is now also using VoIP and they are mixing ports up? Haha, just joking.

 

Another easy thing to check would be that you have enough RTP ports. Having 1000 RTP ports does not hurt, even if you have far less calls.

 

If the problem does not go away, you might have to start Wireshark (maybe rotation mode) on the system. This will involve some data mining, but then the root of the problem will become obvious.

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Whow maybe Sprint is now also using VoIP and they are mixing ports up? Haha, just joking.

 

Another easy thing to check would be that you have enough RTP ports. Having 1000 RTP ports does not hurt, even if you have far less calls.

 

If the problem does not go away, you might have to start Wireshark (maybe rotation mode) on the system. This will involve some data mining, but then the root of the problem will become obvious.

The RTP range is from 49152 to 64512 which is over 15 thousand.

I don't think it is rtp crossing, it sounds more like the call is going to the wrong number, the other party always picks up hello, they must of heard ringing, which does not come from the rtp.

I first called Broadvox as I thought they are routing the calls to the wrong IP or have a backup route set to a bad phone number.

 

However they checked and they say they sent the calls to our number, and I do see the same in the call logs.

 

The problem I may have with wireshark is, the amount of time it takes to reproduce the problem.

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Whow maybe Sprint is now also using VoIP and they are mixing ports up? Haha, just joking.

 

Another easy thing to check would be that you have enough RTP ports. Having 1000 RTP ports does not hurt, even if you have far less calls.

 

If the problem does not go away, you might have to start Wireshark (maybe rotation mode) on the system. This will involve some data mining, but then the root of the problem will become obvious.

I got a wireshark trace, what should I be looking for, there is so much in there, I had to let it run for 30 minutes in order to reproduce.

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