SOLVED Rapid succession of pulses upon answering some incoming calls

domiflichi

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I've got a strange problem happening on our phone system. Sometimes when we answer an incoming call, we hear a rapid succession of pulses (as in the old pulse dial pulses) for a second or two right after picking up the call.

This is a new Incredible PBX 13-13.8 (Whole Enchilada) system that I recently built. About a dozen extensions. Most of them are Snom 320 phones. There is 1 Snom 220. And we recently added a Snom D345.

Again, the rapid succession of pulses don't happen on every incoming call. And it's only at the very beginning of the call. And I haven't had any reports of hearing them on outgoing calls.

We have 6 analog land lines. They are being provided by a local 'cable' company, Wave Broadband (formerly Astound Broadband). They call them VoIP lines, but they look/act just like regular analog phone lines. Coming out of their equipment are just regular Cat3 cables with plain old RJ11s at the ends.

Up until recently we had those RJ11s plugged into a couple internal Digium cards in our old PBX-In-A-Flash system. We never had this weird pulse noise problem with this configuration. But our old system and the Digium cards in it have been dying so I started to build a new system (the Incredible PBX 13-13.8 system that we're on now) to replace it. Instead of buying new internal Digium cards, we decided to go with SIP gateways. We bought 2 Sangoma Vega 60G FXO (4-port) gateways. I didn't want to change everything at once so I set up the Sangoma gateways while we were on the old phone system. I actually did it in 2 phases. The 1st phase I moved the phone lines out of 1 of the 2 Digium cards into one of the Sangomas. I actually only had 1 at this point because I thought we would be actually using 1 of the 2 Digium cards in the new phone system. Later, we decided to phase out the 2nd Digium card so I bought a 2nd Sangoma gateway and moved the remaining phone lines which were plugged into the 2nd Digium card and plugged them into the 2nd Sangoma gateway.

Phew, if you got through that last paragraph, thank you.

Moving on, at some point while on the old phone system and on the Sangoma gateways, we started having this problem of hearing the rapid pulses at the beginning of an incoming phone call. From what I was hearing, everything seemed OK for at least a day or 2. Then the problem started getting worse as time went on - the pulses were happening on more and more incoming phone calls. And they may have lasted longer. We had 1 or 2 people that were calling in to us say they couldn't even hear us speaking at first.

By this point I had the new phone system ready to go, and was hoping that this issue was with the old dying phone system somehow even though the phone lines weren't physically connected to it anymore. I was wrong. Yesterday I moved us over to the new system (the Incredible PBX 13-13.8 Whole Enchilada) that I mentioned in the beginning of this post. And by the end of the day I had a complaint of the pulse sound issue upon answering an incoming phone call.

I have 6 trunks - 1 for each of the 6 phone lines. Following is one of the trunk's settings (they're pretty much all the same, just different trunk names, use contexts, usernames, and secrets):

Code:
Outgoing:
Trunk Name: sgsangveg1

PEER Details:
username=sgsangveg1
type=peer
trustrpid=yes
sendrpid=yes
secret=therealsecret
qualify=yes
insecure=very
host=dynamic
dtmfmode=rfc2833
disallow=all
allow=ulaw



Incoming:
User Context: frm-vega60-1-1

USER Details:
username=sgsangveg1
type=peer
trustrpid=yes
sendrpid=yes
secret=therealsecret
qualify=yes
insecure=very
host=the.IP.of.my.IncrediblePBX.System
dtmfmode=rfc2833
disallow=all
allow=ulaw

If I haven't mentioned it already, I've never configured any sort of SIP gateway before so I'm hoping the strange problem I'm having is just a mis-configuration issue on my part.

I can provide screenshots of the configuration of the Sangoma gateways if that's helpful. This post has already gotten pretty big so didn't want to make this one post even larger.
 

atsak

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I stopped using the Vega's for this reason; weird stuff like this happened I couldn't explain - strange noises etc, not pulsing like you suggest but other squeal type noises were common. Consider trying out a Grandstream gateway and see if the issue goes away. Unfortunately that will cost you to experiment but that fixed it for me.
 

domiflichi

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Oh man, I did not want to hear that.

I'm going to contact VoIPSupply (where I got them from) to see what they say, but I'm hoping someone here can offer some additional insight.
 

islandtech

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Sounds like answer supervision isn't seen and what you hear is the ringing voltage
 

domiflichi

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I contacted tech support @ VoIPSupply.com. They got back to me pretty quickly actually, and their initial response was:

Under the "FXO Hardware Profiles", ensure that "Full Scale" is disabled. This issue is occurring due to the impedance levels.

I checked this and it was already disabled. I emailed them back to let them know, and again, within a couple hours, they replied with a bunch of instructions to do a debug log and a network capture. Both of which are easy to do because they're built-in features so I didn't have to use Wireshark or anything.

I just sent those files off to them a minute ago, so I'll keep you guys updated. I really hope they can help me resolve this. If I have to fork out a ton of money to Sangoma, my boss is gonna kill me.
 
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atsak

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Funnily enough the support contract cost more than the Grandstream, so I set the Vega aside as a backup for emergencies. But I hear you.
 

domiflichi

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Well, it looks like this issue is fixed. After a couple more exchanged emails between me and VoIPSupply, they said the logs are showing that it looks like the Vega's are getting 'overloaded' (or something like that). Then in another email they asked me several questions:
Have you tried performing a power drain on the device instead of rebooting? Have the lines been tested from a buttset as well? I looked at the call samples and it seems that something is getting overloaded. Also, is the DSP firmware up to date on the Vega?
Then shortly after that (before I had a chance to respond to that email) they sent me another email that asked me to try something:
Please add 1 second delay via the Inbound Routes shown in the screenshot attached on the PBX side.
The IncrediblePBX interface didn't let me do a 1 second delay so I did a 2 second delay. I haven't had a report of the problem since doing this (a couple weeks ago now).

Hope this helps someone out there. Marking this thread as solved.
 
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