Whirlpool

I have put my own posts in on this topic and I have read all the others. I am coming to the conclusion that there is *no reliable solution* to the echo problem on PSTN calls when using an SPA-3000 as the PSTN gateway to Asterisk. I am trying to get an SPA-3000 working because no other equipment I know of (including pstn cards on the computer) solves the problem that the SPA-3000 handles well - i.e. automatically cutting over to PSTN when the power goes out, or the Asterisk server goes down. That is why I have been doggedly persevering with the SPA-3000.

I have spent the past two months trying every imaginable combination of gains and impedances on the SPA-3000 - both on line 1 and on the PSTN line. For the last week, it has been without echo and I was beginning to feel I had licked the problem. Then today, an incoming PSTN call came in with really bad echo! The call was from the next suburb and quite loud. I am beginning to wonder if the problem is that Telstra makes some PSTN calls louder than others and when they are too loud, the SPA-3000's echo canceller just can't cope.

What might be needed is some kind of automatic gain control box that sits between the PSTN line and the SPA-3000 and controls the analog signal levels that get into the SPA-3000.

Anyone have thoughts on this?

Rodt,

Take a look at this post for my solution to this problem... forum-replies.cfm?t=455011#r15

TIG

I think rodt is pushing the PSTN into asterisk and therefore bypassing the Spa3000 is probably not an option?

Rodt is the echo at your end or the callers or both?

another (more expensive) option, is to setup the SPA3000 to not send the call to asterisk or Line 1, add a TDM400 to asterisk and connect the PSTN line to both the SPA3000 and the TDM400.

That way the PSTN calls go into asterisk via the TDM400 when there is power, when there is no power the relay closes in the SPA3000 and connects the phone directly to the PSTN line.

Spudling writes...

another (more expensive) option, is to setup the SPA3000 to not send the call to asterisk or Line 1, add a TDM400 to asterisk and connect the PSTN line to both the SPA3000 and the TDM400.

Spudling,]

Now this is what I had in mind for the weekend ahead, as you have touched on the subject what would the settings be on the SPA3000.

Cleve

Have you looked at the Draytek 2100V (cable) or 2500V (ADSL)? Both these have fallover to PSTN when power goes out, but I don't know about the Asterisk thing. Presumably if power is out you have no Asterisk. The Draytek forums are worth a look. People say good things about Draytek. Just got one myself, but it is still in the box.

Hi Rod

From reading this and a couple of your previous posts, I think that you may have a very similar setup to mine....Voip and family...I too have to get the W-Tick (wife tick - a lot harder to get than a A-tick or FCC approval) before anything gets rolled into the Family production environment.

Yes, we also still have a cordless sitting on the bench connected straight into the POTS, removal of such still not W-Ticked.

Anyway my OLD setup
P1. Cordless straight into POTS - "Answerme" phone
P2. Cordless Into FXS port SPA3000 - "Dial Me" phone-->Router ---> Astratel
I had Spa3000 PSTN-->Voip GW disabled, so it was baby steps for the family intro to Voip.
GLW and kids got used to this setup pretty quick and I have saved a fortune - which then allowed me to purchase a SPA2100.

NEW setup as above with
Spa3000 PSTN-->Voip enabled
A@H box intercepting the incoming and handling outgoing to Astratel.
P3. Corded telstra into FXS port SPA2100 Daughter#1's extension.
P4. Soon to be another phone into 2nd spa2100 FXS port - Daughter # 2's Extension.

I must have rushed the A@H box into the family production environment too quickly because when the GLW answered her first Pstn--->Spa3000-->A@H--P1 extension, phone call, from of all people the mother in ulaw. All hell broke loose.
"quote - well you can forget that - if that's the call quality (echo,scratchy & volume) - then forget it - you may as well put that old PC (A@H) back in the cupboard and go back to the two phones" - both daughters upset seeing their "Own" extensions flying out the window.
aaahhh Family harmony....

Hmmm...Back to Systest....
Gain/Impedance/codecs/A@H changes - you name it...
Anyway back in production now with A@H W-Tick approval pending.

Happy to help, if I can, with any questions, settings or otherwise.

Cheers,
Andrew
Edit Spelling..

Spudling writes...

That way the PSTN calls go into asterisk via the TDM400 when there is power, when there is no power the relay closes in the SPA3000 and connects the phone directly to the PSTN line.

I like your thinking Spudling - Can you get a TDM400 with just an FXO port? if so How much are they?

yes - $224

www.techtopia.com.au/pro.../products_id/964

ozvoip.com/showProduct.php?device=tdm01b

Contact Mark at MBIT, great person to work with.

mark@mbit.com.au

www.mbit.com.au

Cleve

I've got the spa-3000 using Asterisk with no problems.

I read about the problems people were having before I bought it but I went ahead and bought it anyway.

The steps I took:

- Made sure I had the latest firmware
- The basic spa settings are taken from the JMC guide
- Forwarded calls from the SPA directly to the Asterisk box (Asterisk forwards to extensions, call is answered if they pick up)

I've also just got a SPA-2100 for more extensions, working good so far - I used similar settings for gain/impedence from the PDF.

If you like a can upload my configs for Asterisk and the SPA

rodt writes...

I am beginning to wonder if the problem is that Telstra makes some PSTN calls louder than others and when they are too loud, the SPA-3000's echo canceller just can't cope.

I agree with Rod - I've noticed that every now and again when I get an incomging via spa3000 --> PSTN --> A@H that the callee gets an echo and it only seems to be when the callee is on the same exchange Edit: Out of interest rod which exchange are you on?

some kind of automatic gain control box that sits between the PSTN line and the SPA-3000 and controls the analog signal levels that get into the SPA-3000.

Does anyone know of such a device??

Spudling + Newboy
Have I got this right?

Mbit
TDM400P + X100M
$115 + $121 =$236

Techtopia
TDM400B + ???
$114 + $110 =$224

OZVoip
TDM400P + TDM01B
$? + $? =$249

So the obvious questions are -
What's the difference between a TDM400P / TDM400B ?
What's the difference between a X100M / TDM01B?

Is the Call Quality from
PSTN --> digium card --> A@H --> Extn, Noticeably better than
PSTN --> SPA3000 --> A@H --> Extn

Cheers
Andrew

TDM400P is the naked card
X100M is the plug-in FXO module
TDM401B is a *B*undle of the TDM400P + X100M plug-in FXO module

Edit: @rodt. I can see why you want PSTN fallback, but seriously I'd just get a UPS and keep a wired phone plugged in somewhere with the ringer turned off for the remote possibility that you need to make a call after the power has been off long enough to exhaust the batteries on your UPS. Train the kids that the wired phone is the hotline to 000.

rodt writes...

I have spent the past two months trying every imaginable combination of gains and impedances on the SPA-3000 - both on line 1 and on the PSTN line

Been there done that :( and still echo. I have also messed with line filters with limited success.

I am beginning to wonder if the problem is that Telstra makes some PSTN calls louder than others and when they are too loud, the SPA-3000's echo canceller just can't cope.

I think it's a known fact that the echo canceller isn't that good.

I have found that it also depends on the person using the phone. We have received PSTN calls and the misses has picked up the phone. She complained to me about echo. I tested with the same call talking to the same person and found that no echo was there. Handed the phone back to the misses and she continued to complain about echo.

I know that the SPA3k has a config option for everything under the sun, but it doesn't have one for my misses :(.

VoIP calls are perfect. So now I just tell the misses to call them back. No echo and a happy misses. We are still saving money doing it this way. It would be nice if SPA could fix the echo on the PSTN.

KS

I like Spudling's solution using a TDM400 along with the SPA3000. To save money, I could sell my SPA3000 on e-bay and use the ILS1002 switch mentioned by the The IT Guy to bypass Asterisk when the power goes down.

leeaijj writes...

Does anyone know of such a device??

Yes their is.

Just in the process of ordering a couple of units. Have a look at this thread.

forum-replies.cfm?t=455011

Cleve

Grubs writes...

Train the kids that the wired phone is the hotline to 000.
Or do as I have done and put a phone bar on the PSTN phone. This way you can receive PSTN calls on it, but not make any unless you enter the passcode. It basically locks the PSTN phone so the kids/partner doesn't use it.

It doesn't take long for them to realise they have to use the "other" phone to make calls :)

Echo in the SPA-3000 is a common problem. In reality, most of the time the SPA-3000 isn't causing the echo, it's just making it more noticeable. This is due to the fact that the SPA-3000 passes calls from the PSTN to the LINE1 by converting it to VoIP internally and then back to analogue. This process does not produce any echo, however is can add about 30ms of latency to the call. This added latency can make echo that was previously unnoticed suddenly become annoying. A pure digital system has no echo (the TX and RX path are 100% separated). It's the interaction of the Digital and Analogue that cause problems.

This may help getting rid of that pesky echo on your Sipura SPA-3000 PSTN line:

1. Make sure you are running the latest firmware (3.1.7) and you have everything back to factory defaults or at least undo all the previous tweaking.

2. Switch *off* all echo can in all your devices. There are 6 places in the sipura to switch off echo can. PSTN Line -> "Echo Canc Enable", "Echo Canc Adaptive Enable", "Echo Supp Enable" and Line 1 -> "Echo Canc Enable", "Echo Canc Adaptive Enable", "Echo Supp Enable". The idea is that we want to hear how bad the echo is with different configs.

3. Unplug everything from your phone line except the SPA-3000. This includes all the extension cables even with nothing connected to them. These can cause impedance problems which lead to echo.

4. Set the Impedance on your lines. PSTN -> "Port Impedance" = 220+820||120nF as a starting point. Regional -> FXS Port Impedance = "220+820||115nF" as a starting point.

5. In the PSTN tab set - "Tip/Ring Voltage Adjust: = 3.1V" and "Operational Loop Current Min = 16mA". Doesn't seem to affect echo, but I believe that these are the correct numbers for Australia.

6. Turn down the jitter buffers! "PSTN -> Network Jitter Level: = low", "PSTN -> Jitter Buffer Adjustment: = disable". This reduces the delay across your SPA-3000. "LINE1 -> Network Jitter Level: = low", "LINE1 -> Jitter Buffer Adjustment: = up and down". If you are using a poor quality VoIP service as well as the PSTN then you could change the "LINE1 -> Network Jitter Level: = medium".

7. Set the preferred codec for the PSTN to be g711a and lock it in. "PSTN -> Preferred Codec = g711a", "PSTN -> Use Pref Codec Only = yes". Obviously adjust this if your accessing your PSTN line via VoIP from a remote network. Set the LINE1 to allow g711a as well as whatever else your prefer- "LINE1 -> Use Pref Codec Only = no". The g711a is fast to encode and decode. Using this codec again reduces your latency and may make the echo less obvious or easier to catch with the echo canceler.

7. Power cycle the SPA-3000 (pull the power plug). Believe it or not, this sometimes fixes the problem. Especially after you have changed the physical phone wiring.

8. Make some test calls. The telco test number 1800801920 is a good one to start with. It has a recorded voice telling you your local phone number. While it's talking, talk back and work out how much echo you are getting. Talk loud, talk soft.

9. Look at what you have got. If you can hear an echo then the problem could be that your probably sending to much power down the line. This is probably reflecting back somewhere as an echo. If your close to the exchange and have good wires then this is probably the case. You need to crank back on the power. Go to PSTN -> "SPA To PSTN Gain" and turn it down. Be aware that at some point if you turn it down to much, the SPA sorts does a double negative and turns it way up. I believe the range of this variable is about -127 -> 127 (from my testing). Turn it down, down, down, down until the person can still hear you but reduced echo. Note: if you enable "Echo Supp Enable" then you will negate these parameters. It seems that the Sipura echo suppression is actually just an automatic gain control. It's really annoying - leave it off.

8. Make a test call to someone with a known good phone out via the SPA's PSTN line or get someone to call in to the PSTN line. Best if its just a boring old telstra phone hard wired to a socket on the wall. Don't call a mobile!

If the remote party is hearing echo, it could be that your phone is so loud that it's feeding back into the microphone. Turn down the PSTN To SPA Gain until you can comfortable hear the person, no more. If the remote user can still hear echo, try using a different phone plugged into the SPA. Go for the basics first, a cruddy old telstra phone is what I use for testing. If this solves the problem you may have a bad phone or an impedance miss match between your phone and the SPA. Try changing the Regional -> FXS Port Impedance to "600". Try changing the FXO port impedance to "600" or "global". If this doesn't help, change it back. The impedance will only affect what the *remote* party hears, it won't help echo you are hearing.

11. After you have the echo down to a reasonable level, go back into the "PSTN" tab and switch on the "Echo Can Enable = yes". Check to see if the echo has improved. If the echo is tolerable at this level, leave the adaptive echo canceler off. You should have the echo level down to a level that can be stomped on by the echo canceler. If you are using a sip device to talk through your PSTN line, you should probably do all the echo cancelation at that device and leave it switched off in the SPA.

The adaptive echo canceler is a lot more aggressive but also can cancel out some of the incoming conversation. In particular if your calling in a loud environment then the voice going down the line from your end can trick the echo canceler to start canning some of the real conversation. It makes the incoming party sound a bit scratchy. Leave it off unless you really need it.

The "Echo Supp Enable" switches on automatic gain controls. This means the sipura will be constantly turning up and down the volume of the call for you and the remote party to try and keep the sound levels at a "good" level. Sipura's definition of good may not suit your situation. The constant variation of the volume annoys me so I recommend leaving it "off".

12. Test call. Talk loud, talk soft. Is your conversation clear at both ends? Should be a lot better. If echo re-appears, at a later date, remember to try power cycling the SPA before you tweak with anything. It may also be at the other end of the call.

In the end it basically boils down to this - If you are hearing the echo, the real problem is at the *other* end of the connection. In a normal phone conversation, the latency is so low that you don't notice it. Your brain automatically tunes out to its own voice when your talking (as long as the delay between talking and hearing isn't to long). When you insert the SPA, the delay is increased and sometimes the echo can become noticeable.

The only way you can counter this is to reduce the latency (jitter buffer) and/or reduce the gains so the echo volume is reduced below the level that it is noticed. At this point, the SPA-3000 echo canceler should be able to kill off the rest.

Good luck.

Tony writes...

This may help getting rid of that echo:

Thanks for that post Tony.

Thanks Tony, awesome resource mate, very nicely done.

Whilst i can't find a perfect echo free balance you have improved the call quality to a point where the boss (wife) can no longer pick the difference between a VOIP call and the land line.

Great work.

that sounds like a good guide, anyone else tried it with success?

I've had echo forever with my SPA3k. My fix was to roll back to version 2.17 firmware. After reading this thread, I thought I'd give it another whirl. I found several things improved it:
1/ Doing a factory reset and starting again. (I had the same settings, but it was better.)
2/ Powering down and doing a cold re-boot (as recommended above).
3/ Reducing the SPA->PSTN gain.
4/ Setting the PSTN LINE jitter buffer to low.

Number 3 surprised me, but thinking it through it should not have been a surprise. I had been trying to reduce the PSTN-SPA gain and the FXO out gain to make things quieter, but this was the wrong move.

If the output to the PSTN is too high, then of course any impedance mis-match (and there are always some) has more power to reflect back... meaning more echo. By reducing the output to the PSTN, the echo gets much less... almost none.

Thanks for the great post!

Did I say version 2.17??? Typo, should be 2.13.
Please don't whim me anymore for version 2.17.
Sorry for the stuffup.
:-)

That will explain why I PM'd you for it a couple of days ago!

Tony writes...

This may help getting rid of that pesky echo on your Sipura SPA-3000 PSTN line:

Brilliant help thank you Tony! I have been searching the Forums for ages, and trying all the "fixes" with gradual improvement, but still bugged by that "pesky echo"

I put some of your advice into my SPA3k and finally, NO ECHO at last!
Thank you! Thank you!

Regional -> FXS Port Impedance = "220+820||115nF" gave me a dreadful mess so I switched it back to "220+820||220nF" now fine again ...

I think the magic came from Paragraph 6 (and both Paragraph 7s)
(Preferred Codecs) and (Power Cycle to set it all in concrete).

You have made my day!

The Telco test number works fine from my landline, but doesn't want to work for me through the SPA at all?? Am I doing something silly?

Don

Wrinkly writes...

The Telco test number works fine from my landline, but doesn't want to work for me through the SPA at all?? Am I doing something silly?

Yes I was! I could make phone calls alright, but could not answer incoming calls.

I had to change the PSTN "Use preferred Codec Only" back to "No"

Now I can answer incoming calls, and the Telstra lady (1800 801 920) now tells me my phone number again!

Time will tell whether the echo has still gone or not.

I will have to wait until someone rings in, for a proper test ...

Out of curiosity, what level do you have your SPA To PSTN Gain set to?

Wrinkly writes...

I had to change the PSTN "Use preferred Codec Only" back to "No"

It should work with that set to yes as long as the FXS port is allowed to use the same codec. I normally let the FXS port (line1) choose any codec and lock the PSTN down to only g711a. When a call comes in, check to see what codec is being used. Use the info screen *during* a call.

mister e writes...

what level do you have your SPA To PSTN Gain set to?

In the end I have gone back to next close to default setting for the gain. I am also running the 3.1.3.a firmware after a recomendation in another forum that was from sipura saying it was the bext to run at the moment until the *new* soon to be released firmware is released. I have been getting very crisp and clear PSTN calls.

Also, don't set the jitter buffer down below medium. There is some bug that causes silent calls and calls to drop out audio when the jitter buffer is set to low. I hope this gets fixed in the next FW release.

When using the 1800 test number. Try waiting until they stop talking after announcing the number 3 times. When the recorded announcment is playing, the echo canceler can't lock in on the echo very well. As you don't generally talk over the top of people it's not a problem in real calls.

Thanks for the input - will give it a try :)

I've been battling with Echo on my PSTN line since day one using Asterisk and X100p cards, I thought the answer was to get an SPA-3000, it was not although I do have to say that the echo was better than than the X100p.

On finding Tony's instructions I began my anti-echo quest again but whilst I got a bit of an improvment I could not get rid of the echo without using Echo Canc Adapt, this takes some time to get the echo corrected (15secs about) by which time the call has failed the wife test.

The echo I'm getting is my end not the remote end.... anyway since getting my SPA-3000 I've also upgraded Asterisk and noticed in the zconfig.h file a new zaptel echo canceller called ECHO_CAN_MG2 (MG2), I compiled the driver with this and tried it out by plugging my PSTN line back into the x100p card - no echo at either end!!!

I live in the UK and my PSTN line is from BT so maybe this is why Tony's instructions did not work for me but I thought some of you maybe interested in this.

Lets hope the next version of the SPA firmware has something like the MG2 echo canceller in it! Linksys are you reading this?

The SPA only has enough CPU power for a very basic echo canceler. It won't ever be able to compete with a PC running asterisk. Lets hope the next hardware revision, maybe the SPA-4000 will have a better echo canceler.

HarvSki writes...

The echo I'm getting is my end not the remote end....

Does that mean you hear an echo of yourself HarvSki?

Tony writes...

The SPA only has enough CPU power for a very basic echo canceler. It won't ever be able to compete with a PC running asterisk. Lets hope the next hardware revision, maybe the SPA-4000 will have a better echo canceler.

It doesn't need much of an echo canceller, anything else is usual problems with impedence and throwing echo cancelling at it is bandaiding the problem rather then fixing it.

HarvSki writes...

Lets hope the next version of the SPA firmware has something like the MG2 echo canceller in it!

Just a note to let you know that 3.1.10(GWd) firmware did a good job for me. No echo on pstn - voip calls. Spa3000 settings are SPA To PSTN Gain:1 and 8 for PSTN to SPA Gain. ( It could be different for other Voip ServiceProviders etc - so test)

Although the release notes say very little on 3.1.10, it seems better for me in just this one very important are

Hope this helps - Marty

Tony writes...

The SPA only has enough CPU power for a very basic echo canceler

This seems quite plausible, but do you know it for a fact? I hope you're wrong, but I suspect you're right.

Wouldn't it be great if linksys did a trade in deal on the SPA3k - return your old SPA3k and $50 and receive a new SPA4k. Sorry, I'm just day dreaming...

I see that the "impedance" furphy has cropped up again on this thread. This has been debated many times, and I concluded that the SPA's PSTN echoes are *not* port reflections. They're natural line echoes, which are incurable - the SPA needs a bigger "Bandaid".

I could live with an echo BUT I have the call drop when I am calling a pstn number , I dial out into the local dial tone and can talk for about 5 mins....the call drops... any help would be appreciated. please Whim me or answer here

Tslam writes...

This seems quite plausible, but do you know it for a fact? I hope you're wrong, but I suspect you're right.

Have a look at www.voip-info.org/wiki/view/Sipura+3000 . They mention that the CPU is an ES3890 controller which was originally designed for playing back video CDs. I would expect that this CPU isn't the worlds most powerful. In any case, the specs of the SPA-3000 say it has a 8ms echo tail. This is going to start to struggle with mobile phone calls which is where I get most problems with echo. For the money however it's a great box. If you need better quality, then shell out an extra $1000 and get a better box.

bluebay writes...

Although the release notes say very little on 3.1.10, it seems better for me in just this one very important are


I tired 3.1.10 and found it wasn't any better in echo then 3.1.7 and to me still sounded a little worse then 3.1.3a. It's a very subjective test however and I am sure people's mileage will vary.

Tony writes...

I tired 3.1.10 and found it wasn't any better in echo then 3.1.7 and to me still sounded a little worse then 3.1.3a. It's a very subjective test however and I am sure people's mileage will vary.

For what it's worth, I am back to 2.13 again. It seems to be the only one that passes the WAF test and has minimum echo.

Sorry for the slow responce, AU is a long way from UK ;)

Yes I here the echo in my ear the other end sounds fine (most of the time)