Good point - regardless of how good 3CX is, if you can't get the handsets working then the overall customer satisfaction is going to be fairly low.
The Linksys phones do look quite nice, so it may be worthwhile persisting with this one by trying something similar to my comments below...
PSTN line echo problem on Linksys equipment.
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During testing, the line echo problem occurred whether or not there was a PSTN line plugged into an SPA-3102 - due to most Linksys devices having an amlost identical GUI, these should settings translate to other devices as well.
I am hoping the information entered in this post will help people that have line echo problems with the Sipura/Linksys units. I have heard reports that these changes have managed to reduce the line echo significantly, down to the point that it is barely noticeable.
The steps listed here are almost going to be taken literally from the document listed on the Linksys site(see link below), the settings listed here are what has been tried previously. ( these maybe slightly different to the original document in the Linksys knowledge base - see link below.), I certainly hope this information helps people reduce echo problems.
NOTE: the settings in this document are for use within Australia and some small modifications would be required to suit other countries.
Step1:
Ensure you modem is running the latest firmware, and *SHOULD* be be set to the factory defaults, or least undo all the previous tweaking.
NOTE: I am running the latest firmware, but I have not reset the modem back to factory defaults
Step2:
Disable all the echo cancellation functions of your SPA-3102, these settings are located on line1 & the PSTN Tabs, (Do this for each tab)
Echo Canc Enable = No
Echo Canc Adaptive=No
Echo Supp Enable = No
Step3:
Remove any devices connected to your phone except the SPA-3102, this avoids any impedance mismatches caused by other devices on your phone line, impedance mismatches can cause echos.
NOTE: if your using ADSL for network connectivity, do not remove your filters from the line to your handset(or the SPA3102)
Step4:
Set the FXO Port impedance on the PSTN tab to 220+820|120nf
Set the FXO Port impedance on the Line tab to 220+820|120nf
Step5:
Look for Network Jitter Level on the PSTN Line tab and set it to low then look for Jitter Buffer Adjustment and set it to disable. This reduces the delay across your SPA-3102.
NOTE: If you are using a poor quality VOIP service, go to the Line 1 tab and look for Network Jitter Level and set it to low and set the Jitter Buffer Adjustment from up to down. But if you are using a poor quality PSTN, set the Network Jitter Level to medium.
Step 6:
Go to the PSTN Line under Audio Configuration look for Preferred Codec and set it to your preferred settings and lock it in by setting the Use Pref Codec Only to yes. Adjust these settings if you’re accessing your PSTN line via VoIP from a remote network then go to Line 1 and set Preferred Codec with the same settings you set with PSTN Line. Under Preferred Codec Only set it no. These settings reduce your latency and may make the echo less obvious or easier to catch with the echo canceller.
NOTE: I have not as yet locked in a Preferred Codec, from the quality of calls I have made , I've noticed that different codecs are used, I'm beginning to think this might be a good idea from the range of calls I have made to land lines and some mobiles and also voip calls.
Step 7:
Power cycle the SPA-3000 by powering down the device. This sometimes fixes the problem especially after changing the physical phone wiring.
Step 8:
Make some test calls and observe if you can hear an echo. If yes, the problem could be that you’re sending too much power down the line and gets reflected back somewhere as an echo. Even if you have good wiring but you are too close to the mouthpiece, you will still hear an echo. To resolve this, you need to increase the level of Gain by going to PSTN and look for SPA To PSTN Gain and slowly adjust the level until you can clearly hear the person on the other line.
NOTE: If you enable Echo Supp Enable, you will negate these parameters. The Sipura echo suppression is just an automatic gain control and it is recommended that it be kept disabled.
Step 9: (note the port impedance in this step is not used is australia)
Make a test call to someone with a phone that works via the SPA's PSTN line or call in to the PSTN line. If the remote party is hearing an echo, your phone may be loud and is experiencing feedback into the microphone. Lower the PSTN to SPA Gain until you can be comfortable hearing the person on the other line. If the remote user can still hear an echo, try using a different phone plugged into the SPA. If this solves the problem, your phone may not be working properly or there is an impedance mismatch between your phone and the SPA. Try changing the FXS Port Impedance to 600 on the Regional tab and change 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 and it won't help remove the echo you are hearing.
Step 10:
After lowering the echo to a tolerable level, go back into the PSTN tab and enable the Echo Can Enable by selecting Yes. Check if the echo has improved. If the echo is tolerable at this level, leave the adaptive echo canceller off. You should have the echo level down to a level that can be filtered by the echo canceller. If you are using a sip device to talk through your PSTN line, you should probably do all the echo cancellation at that device and leave it switched off in the SPA.
Link:
http://linksys.custhelp.com/cgi-bin/linksys.cfg/php/enduser/std_adp.php?p_faqid=5167&p_created=1168646951&p_sid=II4Twyyi&p_accessibility=0&p_lva=5167&p_sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3Jvd19jbnQ9NyZwX3Byb2RzPSZwX2NhdHM9MTcyMSwxNzIzJnBfcHY9MS4yNDMmcF9jdj0yLjE3MjMmcF9zY2ZfbGFuZz0xJnBfcGFnZT0xJnBfc2VhcmNoX3RleHQ9ZWNobw**&p_li=&p_topview=1
Cheers, Brendan
