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Losing audio on incoming calls

Started by M105, April 28, 2011, 07:02:52 PM

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M105

I have a problem that so far I have not been able to solve.  It occurs frequently on incoming calls.  I answer the phone and start talking, then usually after 1 to 2 minutes into the call the audio goes silent.  The other party can hear me but I cannot hear them.  Most of the time, after about 10 seconds of silence the audio will return to normal.  I have had this happen multiple times on the same call.  I would also note that it does not always happen but in the last few days it is occuring on almost 75% of incoming calls.  If I place the call this happens much less frequently maybe 1 out of ten calls.

I am running a Netopia 3347-02 (bellsouth version) router on DSL extreme 3.0.  I have set the router firewall to "Clear Sailing" and opened all the recommended ports 5222TCP, 433TCP, 4893UDP, 19295UDP, 19302UDP, and 19294UDP.  I have the OBi110 configured to a static IP address on my network 192.168.2.24  with 255,255,255,0 netmask.  Opening the ports did not appear to help this problem at all.  It acted the same way with the firewall set to "Silent Running".

I have used the same router etc. on VOIP with a PAP2NT for a couple of years with no problems.  With the Obi and Google Voice though, this problem has existed since day one.

Any suggestions? Anybody else experience anything like this?

RonR

I'm not sure where those ports (5222TCP, 433TCP, 4893UDP, 19295UDP, 19302UDP, and 19294UDP) came from, but I don't believe they're interesting to the OBi.

The problem is very likely your router.  You can prove or disprove this by connecting the OBi directly to your modem and seeing if the problem goes away (if the 3347-02 is an integrated modem/router, that's a problem).

The ports you really want to forward are RTP : 16600 - 16998

M105

The port list came from Google.  http://code.google.com/support/bin/answer.py?answer=62464

The 3347-02 is a fairly high end modem-router that has never caused me a problem with anything else.  I don't doubt that it may be an issue here but I would sure hate to have to switch routers just to get GV to work.  I would very much like to figure out what is causing the problem and change router settings if that is it.   I do have an older DSL modem and separate router I can try.  In the meantime I welcome any feedback from any other users who have run into this problem.



RonR

You shouldn't need to forward those ports.

I would suggest forwarding the RTP ports instead (16600 - 16998) and see if that eliminates the problem.  If not, you may have to try a different router.  VoIP audio problems (especially one-way audio problems) are nearly always router/NAT related.

M105

Good idea.  I have forwarded the RTP port range and will see if it helps.  What makes this so tough is that it is intermittent.  It may not do it for 10 calls and then do it three in a row.  It is hard to nail down.  :)

M105

Forwarding the RTP ports didn't help.  I will continue to kick this around and see what if I can figure it out.  I find it hard to believe that my Netopia business class router is not compatible with the GV XMPP protocol since I have been running SIP through it via Gizmo5 for 2 years as well as Echolink and the like.

Has anyone else experienced random loss of audio from the other party on your Obi?  I would love to hear from you.

RonR

#6
Here's some interesting reading regarding one-way audio by Aaron Clauson, the creator of SIP Sorcery, entitled "The bullet proof solution to one way audio: buy a new router":

http://sipsorcery.wordpress.com/2009/12/15/the-bullet-proof-solution-to-one-way-audio-buy-a-new-router/

If you read far enough, he concludes:

"My recommended solution to anyone experiencing persistent one-way audio issues is to forget about all the solutions except STUN (that's STUNv1 – Simple Traversal of User Datagram Protocol). If STUN doesn't fix the problem for you then throw away your router and get a new one."

If you're interested in the deep-down technical details as to why SIP/RTP/NAT is problematic, Aaron has an in-depth description here:

http://sipsorcery.wordpress.com/2009/08/05/nat-rtp-and-audio-problems/

His conclusion here is:

"The best advice I can give to anyone having consistent audio issues on VoIP calls is to google their router model and see if there are any other people having the same issue and if they were able to fix it. If that doesn't yield anything try and borrow a different router from a friend and see if the audio is better with that. If it is I'd personally replace the router as the long term frustration of audio problems on calls far outweighs $100 or less on a new router."

M105

Yeah that is interesting reading and I never had any problems with SIP.  In fact this router is designed for SIP and Netopia even offers a version of it with a built-in ATA!  Apparently XMPP is a slightly different animal.

SteveInWA

Hmm, you mention that your router is "designed for SIP" -- that may be a clue.  I had a router some years back that had some internal settings for SIP, that, when ENabled, caused external SIP clients (softphone or ATA) to NOT work.  So, those router settings had to do with the router itself supporting SIP.  Have you looked for and disabled any such settings?  It sounds counter-intuitive, but it's worth trying.

I agree with Ron that the router needs to be eliminated as the culprit; a worthwhile test would be to put your integrated DSL modem/router into bridge mode (just use it as a DSL modem and temporarily disable the router section), and let the OBi grab an IP address directly from your ISP's DHCP server (if that is supported by your ISP), or else borrow a Linksys or D-Link router, plug that into your DSL box, plug the OBi into the router, and see if that fixes it. 

I have never had to mess with port forwarding, firewall settings, etc, to make VoIP work, when the router is working properly.   I have a friend who had a Actiontec integrated DSL modem/router combo that never worked with SIP, either.  Sometimes the telcos that provide these integrated modem/router boxes have the configurations altered to intentionally disable things like VoIP, although you said your PAP2T worked, so this is a mystery.

One last thing:  have you tried the OBi/Netopia combo with a ITSP other than Google?  It would be helpful to know if it's limited to Google vs. another provider.  Sipgate, for example, is free and works reliably enough to use as a benchmark.  Same goes for a basic/free Callcentric account.

M105

Last question first:  Yes I ran the Obi110 with Gizmo5 SIP for about 3 weeks before they went away.  No problems.

The router does have a setting for SIP passthrough.  I will turn it off and give that a try.  Thanks for the feedback!

RonR

Quote from: M105 on April 30, 2011, 06:24:47 PMYes I ran the Obi110 with Gizmo5 SIP for about 3 weeks before they went away.  No problems.

Unfortunately, that doesn't vindicate your router.  There's a lot of different server software packages out there (Asterisk, OpenSER, etc.), a lot of different ways to configure each, and a lot of different clients (PAP2's, OBi's, etc.).  Different NAT implementations (there's several ways to do it) in different routers can behave well with most of the combinations but then fail with a particular one.  It's a bit of a crap shoot.  Using STUN servers and port forwarding can often help, but some still fail in certain circumstances.

M105

Not trying to "vindicate" the router Ron.  The man asked me a question and I answered it. I am not ready to throw the router away either.  It is a very nice piece of equipment with a 400mw wireless radio.  If there is a way to solve the issue with router settings then that is what I seek.  It will save me and about a million other AT&T customers from having to ditch an excellent piece of hardware.

Your "solution" is noted: Replace the router and crap shoot a new model.  I got it, okay?  It may be my only choice but I don't give up that easily.

RonR

Sorry, M105, I wasn't trying to push you in any direction and didn't mean any offense.  I've had a good bit of experience with router issues and VoIP over the past several years and was only meaning to emphasize "It's a mine-field out there!" in this area.

M105

Solved:
Using the Netopia 3347-02-1006 (AT&T Bellsouth) router with the OBi100/110.  The Obi seems to be sensitive to the ethernet port switch on this and other routers.  It will randomly lose the incoming audio stream and sometimes drop calls completely.  This is more of a switch issue than a routing issue.  This Netopia router has the capability to isolate a single ethernet port and "wire" it directly to the WAN port.  Although this is done with router settings it essentially plugs the OBi directly into the DSL modem.

------------
In the expert/configure/advanced settings, set up two virtual LANS (VLANS).  Both will be "port" type, not global.

Name the first VLAN "MAIN" and include ethernet ports 1,2, and 3 but not 4.  Also include ssid and uplink.  Leave the priority and promote check boxes empty.

Name the second VLAN "Ethernet_4" and include only ethernet port 4 and uplink. Leave the priority and promote check boxes empty.

Be sure to enable VLANS and individually enable both VLANS and save/reboot.  Plug the ethernet cable for the Obi into ethernet port #4 on the router.

This router requires no other setting changes or port forwarding.  The default firewall and other settings work fine.  The only downside to this solution is that it isolates the Obi from the rest of the network.  When it is plugged into port #4 you cannot access the Obi's web interface from other computers on the "main" network.  The Obi can however still be configured through the Obihai portal on the web.  It can also be accessed locally by temporarily plugging it into one of the other ethernet ports.
------------

This is posted with the hope that it will help others with similar issues.  My research indicates that the Obi is very sensitive to ethernet port timings when operating in Google Voice mode.  I would urge the developers to look into this issue and perhaps adjust the firmware to make the unit more tolerant.

RonR

Quote from: M105 on May 03, 2011, 08:16:57 AMThis is more of a switch issue than a routing issue.  This Netopia router has the capability to isolate a single ethernet port and "wire" it directly to the WAN port.  Although this is done with router settings it essentially plugs the OBi directly into the DSL modem.

Haven't you simply bypassed the router/firewall on Ethernet port 4?  Nothing in the Ethernet port has changed.  You're simply feeding port 4 from the input to the router/firewall (the modem) rather than the output of the router/firewall.  In my mind, this is a confirmation that the router/firewall is the culprit.

M105

Quote from: RonR on May 03, 2011, 09:09:13 AM
Haven't you simply bypassed the router/firewall on Ethernet port 4?  Nothing in the Ethernet port has changed.  You're simply feeding port 4 from the input to the router/firewall (the modem) rather than the output of the router/firewall.  In my mind, this is a confirmation that the router/firewall is the culprit.

No, I have set up a VLAN.  The firewall is still in place.  This VLAN isolates port 4 from the rest of the network meaning it does not get broadcast packets from the other three ethernet ports or the wireless port.  It is basically a firewall protected LAN with one NAT routed & firewalled port to the Internet.  The Obi works perfectly with this configuration, the firewall is not and never was the problem.  By putting it on its own virtual network, the link is quiet and not full of broadcast packets from other devices.

I suspect a lot of other "router" problems are really more related to the ethernet switch and are not NAT firewall or routing issues.  I actually think the Obi may be firmware tweakable on the GV service so that it isn't as sensitive to packet timing.  I hope the developers will take a look at this with a more technical perspective than a mere mortal like me can give it.

Also, there is a lot of information about VLANs on the web and many other routers support them.  This may be an easy fix for others experiencing audio loss and dropped calls.

RonR

Curiosity question:

Is your OBi using DHCP, and if so, what IP address is it getting after a reboot connected to your new isolated port 4?

M105

No, I have it set for a static IP.  The address map is still the same as the other VLAN 192.168.2.xxx but the Obi is not reachable from the other VLAN.  I think there is a way to make routing across VLANS possible but this worked so smoothly I saw no need to change it.

M105

Just an FYI to OBi support...  I took my Obi off the VLAN and put it back on the main LAN after reading that the latest firmware update addressed some home router problems.  It seems to be better but it is still not satisfactory.  It will drop audio or completely drop the call at random times.  I had to switch it back to the VLAN port which is isolated from the ethernet/wifi switching.  It works fine that way.

There is still a problem there guys.  Please keep working on it.