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On Wed, 6 Mar 2013, Paul Hirst wrote:
I get terrible echo when talking to people on the DECT phone. Ie I hear myself back, maybe with a ~300ms delay. However the person on the remote end reports that I am very clear with no echo at all.
Echo is *always* generated by the far-end. So you're hearing the reflection of your own voice done by the phone at the far end. Most people will hear echo when the round trip time is over 30mS. Under that and your brains one echo cancellation works. (ie. you only hear what you say once)
The person at the other end does not hear their voice echoed back to them because their using quality kit (ie BT) to manage their calls and their phone provider manages the echo cancellation for them.
You need the device at your end to recognise the echo coming bck and cancel it.
I can't actually get the voice menu to work when people phone my landline number. It doesn't recognise the tones. However when I install a SIP client on my mobile and connect that to the menu system in Asterisk it seems to work perfectly.
You need to make sure that the SPA3000 and Asterisk are talking the same DTMF signalling protocol.
I have read reports that the echo cancelation on the SPA3000 is a bit rubbish and that there is a serious issue with DTMF detection (I followed the instructions to solve it with no success so far). I have tried various firmware versions to try and fix this but nothing seems to have improved it.
At least you haven't lost much money...
What I'd like to know is, should I just give up with the SPA3000, is it too old/rubbish? Is there any other way I can do this on the cheap? (Hopefully <£25). Have I given up too soon?
You get what you pay for...I have had success with the Grandstream boxes, but even then, their echo cancellation hasn't been brilliant.
Asterisk can only echo cancel when it has access to the analog signalling. (ie. with a plugin card) Then it's pretty good. (using OSLEC)
I can't make use of PCI cards to connect to the telephone line because my 'home server' PC is a little nettop box which has no expansions options other than USB.I'd really appreciate any advice you have. I'm disappointed to have got so close yet so far.
Port your number into a VoIP platform (but you'll need to get a new BT line in first and migrate your ADSL) then it will be digital end to end.
Gordon
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