Silent calls on SIP Trunk

[Gunnaro]

Hi guys!

Got an ugly case hanging on my shoulders:

IPO 500 V1, 10 IP extn,IP 1616 phones local powered, 30 sip ch. (they got loads of inbound traffic + twinning on all extn).

Inbound are randomly silent when picking up. Agent sometimes hears rapid busy tone.
If the agent hangs up quickly, the same call starts ringing again, and then it's all fine.

SIP Trunk comes in on WAN (have tried swapping ports on the fibre switch, physically bypassing the fire wall, etc).
Provider of the trunk has done traces and can't find anything wrong.

Phones are on LAN port, together with the computers and servers.

SIP config is a blueprint of a system that has been running flawless for years, with same SIP provider.

Anyone experienced similar conditions?


Kind regards
Gunnar

 

[tlpeter]

What do you see in monitor?
Sounds like a bad VCM card.

BAZINGA!

I'm not insane, my mother had me tested!

 

[Gunnaro]

I thought of that too, but all is fine when using ISDN PRI. Monitor does not give any clues either.
Could be the WAN port gone bad, but I can't see a significant packet loss.

Seems that this occurs more often when there are many callers.

Anyway, I've decided to take the long trip and swap for a V2, put in a new switch and check out the wiring just to be sure.

Kind regards
Gunnar

 

[tlpeter]

That could be a problem too indeed.
Let us know if it fixes the issue.

BAZINGA!

I'm not insane, my mother had me tested!

 

[hairlessupportmonkey]

Ive seen this with a corrupt SIP trunk. The IPO wasn't sending out acknowledgements to the ITSP so the call kept getting represented and the RTP stream wouldn't get initiated.

try deleting the trunk, reboot and recreate it.

ACSS - SME
General Geek

 

[Gunnaro]

Hi Sean & Peter!

On site now, and there are multiple faults within the network...

- Local phone power are connected to weak "desktop UPS", sharing 100 Watts with monitor, printers, PC, etc.
- Computers get LAN access via handset
- Switch is 100 Mbit on all ports, so when workload is at it's highest there is congestion.
- Local dog chewing on cables

So, I physically separated the phones from the computer network, put in a new PoE switch, replaced cables and now things are just fine. (If dog starts chewing again, PoE will curl his whiskers)

Kind regards
Gunnar

 

[tlpeter]

If dog starts chewing again, PoE will curl his whiskers

What kind of dog?
If it is a big dog then he probably won't notice

BAZINGA!

I'm not insane, my mother had me tested!

 

[Gunnaro]

No, small curly thing, 4 kg max.


G

 

[hairlessupportmonkey]

I dare you to chew on 48V and see if you dont notice....

ACSS - SME
General Geek

 

[holdmusic34]

He'll get 100 jolts if he bites the dsl.
Glove up and rub chilli powder on the leads near the cabinet. Don't touch your nutsack.

 

[Westi]

48V DC man I eat that for breakfast

ring voltage here is 90V AC compared to the 60V AC in Germany and I noticed that pretty quick when I got the first ring on my sweaty forearm on an old 66 block terminal.

Joe W.

FHandw, ACSS (SME), ACIS (SME)

http://convergednetworks.ca

“Quality is never an accident; it is always the result of high intention, sincere effort, intelligent direction and skillful execution; it represents the wise choice of many alternatives.”

 

[tlpeter]

Pfff, bit a telex signal
Analog is 48 volts here and ISDN is 90 volts.
But it is the amps that count and not the volts

BAZINGA!

I'm not insane, my mother had me tested!

 

[holdmusic34]

You're not a real tech until you've been zapped on an solder tag MDF during a Friday night relocation to a tall building.

 

[tlpeter]

I once had to rewire 1500 crosswires on LSA+ at Schiphol (yes the airport)
Some stupid %rs digged through some mayor cables.


BAZINGA!

I'm not insane, my mother had me tested!

 

[qtelcom]

So what did you put on the invoice to the customer for work done? Fix SIP ringing issue due to dog chewing on cables? lol...

 

[Westi]

I love Schiphol's toilets with the flies in it. I had a layover once and ran to the toilet just to see it and then ran back to my plane.

Joe W.

FHandw, ACSS (SME), ACIS (SME)

http://convergednetworks.ca

“Quality is never an accident; it is always the result of high intention, sincere effort, intelligent direction and skillful execution; it represents the wise choice of many alternatives.”

 

[Gunnaro]

Well, let me see..

Peter is right, it's the amp's that kills you, voltage just make your dance faster...
And I'm fairly sure PoE will make your tongue-action go Jar-Jar Bings style.

Westi, that's not a toilet, no dumping (but the fly might indicate that someone just did that...)

When it comes to sufficient voltage, a South African gentleman (Dutch judging by the name) did some research on that:

http://localloop.co.za/2009/11/power-over-ethernet-makes-cat5-cable-less-tasty/

Holdmusic, that chilli-trick did not work on my dog, he ate the shoe that I "marinated". Thirsty, though.


Gunnar

 

[hairlessupportmonkey]

OK - to shed some light.

Low voltage high current will not harm you.
High Voltage low current will harm you. It can potentially stop your heart.
80mA THROUGH the heart will burn it.

A 9 V battery on your tongue is unpleasant.


ACSS - SME
General Geek

 

[Gunnaro]

Well, still the Amp is the contributor to death, but higher voltage helps penetrating the skin.

Due to body internal resistance of 400-1K Ohms, and the skin resistance of 1K-100K Ohms, voltage below 50 VAC or 120 VDC will not be able to carry more than 30 mA...so that's why everyone are allowed to play with their 12 volt down light wiring and telephone cables.

I had the "pleasure" of experiencing a tech dropping his spanner on to the terminals of a 2V 2.500 Ah battery cell. No more spanner, no more cell. He lived, but never came back to work.

Gunnar

 

[holdmusic34]

AC and DC Amperage best case scenario risk chart:

Charles Dalziel's risk chart represents best-case scenarios, and do not necessarily reflect the risk to persons in poorer states of health.

http://www.allaboutcircuits.com/worksheets/shock.html

i.e 9 volts can also be fatal depending on the joker getting zapped, duration...

Voltage and amperage best case scenario risk chart:

Three professionals have published in a peer reviewed engineering journal on the subject here:
[URL unfurl="true"]http://www.medwelljournals.com/fulltext/?doi=ijepe.2010.177.181[/url]

Please use as a reference only.