I've been following the list for months, and I have a working Asterisk setup, but it'd be *really* useful to me at this point if someone could summarize when Asterisk has echo problems and when it doesn't. For instance, I usually hear a far-end echo when talking on my 7940, but not when using a POTS phone plugged into a TDM400 FXO port. It doesn't seem to matter if the call goes out over a POTS line or via NuFone; either way there's a fair bit of echo on most (but not all) calls. Do different SIP phones have better echo cancellation then the Cisco 7940/60s? How about the Polycom IP500/600s? Does it matter if calls go out via POTS/T-1/PRI/VoIP? The general impression that I've received is that "fast" channels (basically traditionally telephony interfaces) don't exhibit noticeable echo, but the slight delay associated with VoIP packetization unmasks existing echo. Is that a reasonable summary? We're starting to plan for a new office build-out at work, and I'd love to use Asterisk and SIP phones in the new office, but I'm not going to try to sell management on a phone system with a horrible echo problem, even if it will get fixed eventually. Thanks. Scott
Scott Laird wrote:> I've been following the list for months, and I have a working Asterisk > setup, but it'd be *really* useful to me at this point if someone > could summarize when Asterisk has echo problems and when it doesn't. > For instance, I usually hear a far-end echo when talking on my 7940, > but not when using a POTS phone plugged into a TDM400 FXO port. It > doesn't seem to matter if the call goes out over a POTS line or via > NuFone; either way there's a fair bit of echo on most (but not all) > calls. > > Do different SIP phones have better echo cancellation then the Cisco > 7940/60s? How about the Polycom IP500/600s? > > Does it matter if calls go out via POTS/T-1/PRI/VoIP? > > The general impression that I've received is that "fast" channels > (basically traditionally telephony interfaces) don't exhibit > noticeable echo, but the slight delay associated with VoIP > packetization unmasks existing echo. Is that a reasonable summary? > > We're starting to plan for a new office build-out at work, and I'd > love to use Asterisk and SIP phones in the new office, but I'm not > going to try to sell management on a phone system with a horrible echo > problem, even if it will get fixed eventually.I have an Asterisk system I have been testing for about a year for work and I have NO echo problems. I just setup an * server at home with a generic $11 ebay X100p clone at home and had terrable echo when dialing out POTS. I was able to reduce it by changing the TXgain and echocancel set to on. But its still not perfect like my REAL DIGIUM card in the office PC. I can live with how my home phone is but it would not be good for my office system. Thats what I get for trying to go cheap. I would definately recommend Digium hardware, or at least a major brand supported by * no clones. Kyle www.quadrasoftware.com Asterisk Receptionist, CallerID and applications.
We're using asterisk in production at my place. We have about 45 users (33 snom 200 sip phones and the rest on soft phones). We're connected to the telco via a pri (23 useable channels) using the digium t1 card. We have another t1 card hooked to an adit 600 channel bank for analog services. Internally, sip2sip calls, you can't hear any echo. Anything that heads out over the pri is really pretty good. Unless you have cyborg ears, you don't hear much, if any echo (at least the users haven't complained). One thing that bites on the snom 200 is the speaker. It seems to be very choppy sounding. Someone here seems to think the VOX chip is junk, but I really don't know what the deal is. We've plugged in our normal (analog) conference phone via the channel bank and it kicks butt. The adit 600 is a good device. We can send/receive faxes (the standalone modems seem to be ok as well, though I haven't seen at what rate their connecting at, we only use 'em for payroll and the postage machine so pry 9600). The PoE seems to work flawlessly (we're using the powerdsine 24 port midspans). Out of 33 snom phones, 1 couldn't use PoE (external ps works), 1 worked, but the internal ps seemed to give out, now it won't power on at all, 1 spontanously reboots, and 1 seems to have a problem with it's on hook button. Watchout who you buy them from, as the company we ordered from is a disgrace, getting these rma'ed is a total pain (still not done). I would almost suggest setting yourself up as a reseller and buy directly from the closest distributer (I don't know if they charge a fee or not). On Thu, 2004-07-15 at 16:13, Scott Laird wrote:> I've been following the list for months, and I have a working Asterisk > setup, but it'd be *really* useful to me at this point if someone could > summarize when Asterisk has echo problems and when it doesn't. For > instance, I usually hear a far-end echo when talking on my 7940, but > not when using a POTS phone plugged into a TDM400 FXO port. It doesn't > seem to matter if the call goes out over a POTS line or via NuFone; > either way there's a fair bit of echo on most (but not all) calls. > > Do different SIP phones have better echo cancellation then the Cisco > 7940/60s? How about the Polycom IP500/600s? > > Does it matter if calls go out via POTS/T-1/PRI/VoIP? > > The general impression that I've received is that "fast" channels > (basically traditionally telephony interfaces) don't exhibit noticeable > echo, but the slight delay associated with VoIP packetization unmasks > existing echo. Is that a reasonable summary? > > We're starting to plan for a new office build-out at work, and I'd love > to use Asterisk and SIP phones in the new office, but I'm not going to > try to sell management on a phone system with a horrible echo problem, > even if it will get fixed eventually. > > Thanks. > > > Scott > > _______________________________________________ > Asterisk-Users mailing list > Asterisk-Users@lists.digium.com > http://lists.digium.com/mailman/listinfo/asterisk-users > To UNSUBSCRIBE or update options visit: > http://lists.digium.com/mailman/listinfo/asterisk-users >
> I've been following the list for months, and I have a working Asterisk > setup, but it'd be *really* useful to me at this point if someone could > summarize when Asterisk has echo problems and when it doesn't. For > instance, I usually hear a far-end echo when talking on my 7940, but > not when using a POTS phone plugged into a TDM400 FXO port. It doesn't > seem to matter if the call goes out over a POTS line or via NuFone; > either way there's a fair bit of echo on most (but not all) calls. > > Do different SIP phones have better echo cancellation then the Cisco > 7940/60s? How about the Polycom IP500/600s? > > Does it matter if calls go out via POTS/T-1/PRI/VoIP? > > The general impression that I've received is that "fast" channels > (basically traditionally telephony interfaces) don't exhibit noticeable > echo, but the slight delay associated with VoIP packetization unmasks > existing echo. Is that a reasonable summary? > > We're starting to plan for a new office build-out at work, and I'd love > to use Asterisk and SIP phones in the new office, but I'm not going to > try to sell management on a phone system with a horrible echo problem, > even if it will get fixed eventually.For the most part, echo is less of a problem today then what it was a month or so ago. The source of the echo varys case by case, however key points that need to be addressed in _any_ installation include: - * fxo pstn interface cards (eg, x100p, tdm-fxo) have to be configured to match the impedance of the telco standard for whatever country you're in. The x100p, by design, appears to be limited to a 600 ohm telco impedance (US standard), and will likely generate echo when attached to pstn lines that are not 600 ohms. The tdm cards are different and can be configured to match just about any telco standard worldwide. (Don't know about the x101p, never seen one.) - echo issues with the zap interfaces (eg, x100p, tdm, T1/E1 cards) rely on a software echo canceler within asterisk. If the above impedance match is correct, most implementations seem to have found parameters that minimize echo for them. However, there are still some in which echo is a problem and best 'guess' as of this afternoon is those cases appear to have something to do with undocumented internal system hardware. Some folks have found swapping a motherboard for another with no other changes reduces echo by noticable amounts. That would suggest buss speed, PCI version, or something like that other then processor speed or RAM. There are working examples of 300 mhz machines with no echo, 2.2 ghz machines with echo, and dual processor systems with echo. - Digital interfaces to * (eg, T1/E1, PRI, ISDN) tend to be less prone to echo, however there are some implementations that still have it and non-technical users of those systems do complain. Technical users tend to tune it out. - there has been very little list noise associated with echo that could be honestly pinned on any sip phone. - there's been a lot of opinions stated about the cause of echo on the list, and at least some have no technical factual basis. - there's a rather strong belief that additional echo problems exist within asterisk, and a group of non-programmer types are attempting to isolate common items in an effort to document the problem for those that have the programming skills to address. (That's happening on a non-asterisk email list.) It seems that production systems either don't have any echo issues, or they have objectionable amounts. There does not seem to be anything in between. Its probably fair to say the majority (if no all) developers don't have the problem, making it most difficult to isolate and troubleshoot the cause. Best guess (based only on the list noise level since Octomber 2003) is that probably 80% of the production * systems are near echo free, and 20% still have objectionable echo. Others may argue a different ratio. YMMV. Rich