I posted about this a couple of months ago - a link to the original thread is below. Since, I’ve upgraded the phone firmware, dug into the network side of things, shortened the route to our SIP provider, and asked them to look at their systems for any clues. None have resulted in any improvement or isolated the problem.
In short, there is VERY intermittent ‘static’ in calls, but only the caller seems to be able to hear it when it happens. My hunch is that it’s digitization of some kind, but am going to use ‘static’ to describe it in this post as that’s how it’s been described by our customers. It’s only been reported by our operators for customers who call in; all have Sangoma s500 phones. None of our other users with different brand/model phones have reported it, though this could be coincidence as the operators handle MANY more incoming calls than anyone with a regular DID. The call recordings are clean, which eliminates such things as the handset cord, ‘dirty’ PoE, & other problems between our user and the PBX as then the recording would have the static. It has been reported with customers on cell phones as well as those with land lines.
The primary problem I have in tracking it down is that it’s SO intermittent - we may have one call a week where the customers can’t hear us or we might have two or three inside a 10 minute window. Once a call has the ‘static’, it seems to keep it until the call is terminated. If a customer hangs up and immediately calls back, the ‘static’ is gone. There is no pattern I’ve been able to discern; I’ve checked day of the week, time of day, and wrote a script to track the number of calls active. Doing a packet capture really wouldn’t be feasible given how randomly it occurs.
The only other idea I had was to write something to record how much bandwidth is being used in set intervals and then compare the arrival of the ‘static’ calls with this log, but this is going to be considerably more involved to get it right and frankly, I don’t know if it makes sense. Given that a call keeps the ‘static’ for the duration of the call and other calls can come in clean while the call with the ‘static’ is active, it doesn’t seem to be a limited bandwidth / line saturation problem. Same thing with tracking CPU usage on the PBX - it wouldn’t stay on a call until terminated and would affect all calls at the same time if this were the source.
Is there anything else anyone can think of that I could do to track down & fix the source of this ‘static’? I’m really scratching my head and it’s unbelievably frustrating to not be able to reproduce or even hear it, instead having to rely on our customers to describe the sound. It’s not a huge deal given how infrequently it happens, but is a considerable annoyance to the users & worrisome to me as an indication something isn’t right. Or is this type of thing considered normal for a PBXact-based phone system?
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My extended time off is just an artifact of not having taken any time off all year so far - I ‘use it or lose it’ when it comes to vacation time and would rather use it, even though it’s now cold/snowy out. I GOTTA start taking time off in the summer when I can go drive my boat around and catch fish…