Topic: Incoming VOIP calls causing ADSL drop out

[madadam]

I'm having a very strange problem which I've been unable to find a cause for.

I'm running sail-2.2.1-745 (though it's happened with earlier builds) and every now and then after receiving an incoming call the line goes dead and it turns out my ADSL connection has been dropped. Initially I thought this might be my ISP as you would think. But it keeps happening after an incoming call has been answered, about 3-10 seconds into the call.

Does anyone have any ideas about this strange problem or have they had any similar problems?

Cheers,

Adam

[gippsweb]

Is it an analog or VoIP call?
If an analog call the most common cause of internet dropouts we see are either faulty filters or a dirty connection somewhere in the house/business.....

[madadam]

Is it an analog or VoIP call?
If an analog call the most common cause of internet dropouts we see are either faulty filters or a dirty connection somewhere in the house/business.....

Thanks for your reply.

I'm talking about VOIP calls here. While the ADSL line has an active phone carrier (ie. it is not a naked DSL service) it's only there for emergency use.

It's hard to imagine why an incoming VOIP call might cause the ADSL line to drop out but that does seem to be what is happening.

Cheers,

Adam

[gippsweb]

As I've just had a couple of beers these questions are not necessarily in the correct order..

Is the sail box running in server/gateway mode or server only??

I guess the answer to that answers the next question.......
Is the modem bridged or is it routing everything to the sme/sail box??

What do you have between the sail/sme box and the internet? ie; modem, firewall??

[madadam]

As I've just had a couple of beers these questions are not necessarily in the correct order..

Is the sail box running in server/gateway mode or server only??

I guess the answer to that answers the next question.......
Is the modem bridged or is it routing everything to the sme/sail box??

What do you have between the sail/sme box and the internet? ie; modem, firewall??

Hiya,

My SAIL box is in server/gateway mode and acts as the internet gateway for my small network.

I have a Netgear DG834 modem/router.

Cheers,
Adam

[SARK devs]

For what its worth - we have seen something like this once or twice in our customer base.  It absolutely drove us nuts until we figured it out...   

The first time was with a Draytek router (nice mid range unit).  We didn't fit and had no access to it.  The techs who looked after it were good guys, but they didn't know VoIP, and they had set up a lot of the advanced features on the Draytek, including the DOS UDP attack threshold...  Figured it out yet?   At one call on the circuit, everything was hunkydory, also at two and three, but at four, the circuit went down... for exactly 10 seconds and then resumed nornal operations. 

Turns out that the standard Draytek reponse to an assumed DOS attack is to shut down all comms...  for 10 seconds.

Solution, - increase the threshold at which the DOS attack mechanism kicks in.


Maybe your problem, maybe not


Best

S

[thomasch]

I suggest you to check if ADSL line filter installed. It may cause problems with ADSL modem in general (modem resets, ADSL connection dropped, modem hang) especially if there is a phone (pabx too) hooked in paralel with the modem.

thomasch

[madadam]

I suggest you to check if ADSL line filter installed. It may cause problems with ADSL modem in general (modem resets, ADSL connection dropped, modem hang) especially if there is a phone (pabx too) hooked in paralel with the modem.

thomasch

Hello Thomasch,

Thanks for your suggestion but as discussed above it has nothing to do with interference on the ADSL line which is not used for anything else.

The problem of ADSL dropout only happens on some occasions when you answer an inbound VOIP call. After answering the ADSL drops out after 3-10 seconds.

My ISP delivers a very good ADSL service which can go for months without dropping out. The dropout has only ever happened immediately after receiving a phone call on the asterisk (+ SAIL) server.

Cheers,

Adam

[thomasch]

Thanks for your suggestion but as discussed above it has nothing to do with interference on the ADSL line which is not used for anything else.

Do you use p2p (emule Bittorent)? Too much connection also kills modem. Maybe one VOIP call cause it to trip over the limit.

thomasch

[psoren]

I had some issues as well.
Not a complete drop out, but after a couple of days, mails stopped coming in and it was impossible to access webpages from outside.
It turned out to be my ADSLmoden/router, a ZyXEL Prestige 2602R-D1A. It could not handle all the TCP connections. The limit was at the beginning 2000 connections and i changed it to 6000, but that just gave me a few days more before it went down.
The solution was to change the router to Bridged mode, my SME runs as server-gateway so that does the routing anyway.
All this started after i began using VoIP, so i guess that makes a lot of connections....

Per

[SARK devs]

madadam ...

Did you see our post re DOS attacks?
Have you checked the modem?

Best

S

[madadam]

madadam ...

Did you see our post re DOS attacks?
Have you checked the modem?

Best

S

Hi Guys,

Yes I did see your post thanks. I've been slowly going through a number of tests, each test takes about 2 days due to the random nature of the problem. I tried your suggestion earlier this week. I have a Netgear DG834 G3 modem router which has an option to "Disable Port Scan and DOS Protection" which I tried for a few hours. It actually made the problem worse.

What is happening is that occasionally the sync is lost on an inbound or outbound VOIP call. The modem then needs to resync and re-authorise and that takes about 20-30 seconds.

What's interesting is that the Snom 360 on my desk also registers with another VOIP server other than my own for another business I'm involved in. Calls coming in on that line have also started to cause the modem to loose sync so that discounts my VOIP server as the cause.

I got a replacement Netgear DG834 and first tried replacing the power supply on my modem (I'm told the Netgear power supplies can be faulty yet still power the unit so it looks like it works correctly but when the modem/router draws more power it fails). Anyway that didn't work so I've now put the new modem in place and so far it seems to be working, but I need to test it over the next few days.

Hopefully it was the modem.

Cheers,

Adam

 

[madadam]

Well the new modem/router (Netgear DG834 G3) is working fine and there has been no drop outs on inbound or outbound VOIP calls.

So conclusion is that the original Netgear DG834 G3 modem was faulty even though it seemed to be working fine. It would seem that with all the additional processing the router was doing for VOIP calls  that it just gave up the ghost.

So if you are having problems with your ADSL line dropping out when using VOIP consider trying a new modem/router if nothing else works.

Hope this helps others.

Adam