I have a customer with a 2821 (with 12 FXO ports). I have another customer with a 2811 (with 8 FXO ports) plus 4 remote sites with 2801 routers (each have 4 FXO ports). The FXO cards used in these routers are 2-port FXO's and 4-port FXO's.
All of these are exhibiting the same issues listed here:
1. Echo that we can't get rid of through FXO calls. Some of the sites are better than others.
2. Voice cutout between IP Phone and PSTN via the FXO ports. Example is when the callers at both ends of the call talk at the same time, your voice cuts the other end out. Also, if you are on the PSTN side of the call, and get put on hold (in this case it is CallManager's MOH, and either start talking, breath lightly into phone, or if there is background noise), the other end of the call cuts out. The other example is when you call in from the PSTN, go through the FXO port, and listen to a Unity greeting, and start talking, breath lightly into the phone, or if there is background noise, Unity greeting cuts out. Sniffer captures show no packet loss. IP Phone to IP phone is crystal clear, which the customer loves, but they obviously want their IP Phone to PSTN calls to sound just like the IP Phone to IP phone calls.
3. PSTN call through FXO port goes to IP Phone, then when it is either transferred or Call-Forwarded back out to the PSTN through another FXO port, the call is EXTREMELY quiet.
4. While on a call between IP phone and PSTN, as you are talking or breath lightly into the IP phone, you will hear a fuzzy sound. Its not like the fuzzy sound sample listed on Cisco's support page for troubleshooting voice quality.
Trust me....We've tried every combination of input gain and output attenuation, plus impedance settings, and trying the thl tests.
We've worked with TAC and have brought in some other "higher-ups" at Cisco, but haven't figured it out yet. We are starting to believe it may be an issue with FXO cards on the ISR series. We have another customer with a 2821 using a T1 to the telco without any problems at all, which leads me to believe its an issue with FXO cards and the ISR series.
IOS versions on the routers are either 12.3(11)T5 or 12.3(11)T7. CallManagers are either 4.1(2)sr1 or 4.1(3)sr1. Phone loads are 7.0.2 and 7.2.2. There really isn't anything common except for the fact that they are all using ISR routers.
Has anyone experienced similar issues?
We've replaced the FXO cards. Plus, I've seen this issue on a 2811 and four 2801's. We have a customer using a 2821 with a T1 card to the telco and we don't have a problem with theirs. It seems like an FXO issue on the 2800 series. I've seen some bugs regarding similar issues and other forum posts like this, so maybe Cisco needs to do some further quality assurance on these cards/routers/IOS versions.
Kevin....Did you ever get a fix? I have a similar problem with FXO-4 in a 3725. Seems fine on some line, but awful on others. Driving me nuts.....Mike
I am still battling the issue. It is much better, but the echo still there intermittently. The users had their volume on the phones set to the max, which introduced some of the acoustic echo. Some sites we had to set input gain anywhere from 8 to 11 and the output attenuation around -1 or -2. This seems kind of extreme having the gain that high, but it resolved the hairpinned calls when transferring an inbound FXO call back out another FXO port. We also get an annoying white noise sound sometimes when speaking or breathing lightly. When not speaking, you can barely notice the line noise, but when you start talking, we notice a white noise/fuzzy sound.
One of the most frustrating things is when I leave the customer's site, I make several calls and everything sounds great, but then the next day or two, they call us up and say that the echo is still there. Not all the time and not as bad, but it is still there.
Also, how far is the customer from the telco switch. You don't want it more than 15,000 feet for the local loop. One of the customer's site is about 21,800 which may be some of the problem.
Its not just on the ISRs. We have one of the sites with a 2650XM and the same issue. Not as bad, but still have some echo.
Hope this helps, and I'm open to any other suggestions. :)
Kevin....Thanks for the info on the loop length.
I'm meeting a telco tech on-site to see what we can figure out.
2 strange things:
1 of 3 lines at the site is crystal clear.
If I disconnect the router and put my buttset on the line it sounds perfectly clear.
One of the strangest problems I've seen......Mike
You mention that one of your lines is crystal clear. If you exchange the lines on the router such that one of your "bad" lines is on the port that used to have a "good" line on it, does the problem follow the line that moved or stay with the port? Try to do your tests after-hours when there's little call activity.
If you find that the problem stays with the port, you might be running into an issue like one we found consulting on a troublesome FXO issue with another partner's CallManager Express deal (although this would also apply to CallManager). This customer also experienced extremely quiet calls with mild audio artifacts, and there was also a very high echo-return (but the ECAN was mostly able to deal with it). It's a terribly long shot, and I don't want to get into the long and ugly details on the forum, but ask your TAC engineer to look at service request 602290637 and see if something similar could be happening at your site. If so, there's a workaround. This goes for the original author of the thread too.
Got my problem fixed.
Telco tech found 20V of 'foreign voltage' across the pairs. He says it's usually caused by wet cable.
It was very strange. Line sounded fine with a buttset. Obviously, router FXO port did not like that foreign voltage.
Thanks to all for the suggestions......Mike
Oh, man! We had a TDM site that had wet pairs on a T1 once. It took us months of troubleshooting to figure out what the problem was. We thought it was RFI/EMI coming from NORAD!
Can you describe the problems you were having? Did you happen to get the ERL and signal levels from a show call active voice output?
I like how you worded it "foreign voltage". I'll have to remember that one. :)