Ralf Schlatterbeck wrote:
On Tue, Jun 12, 2007 at 03:48:16PM +0200, Christian wrote:
Kristijan Vrban wrote:
It really depends. When calling a GSM or ISDN phone, I wouldn't need an
EC, calling some analog phones, especially wireless analog phones and I
have sometimes really heavy echo.
I confirm. With mISDN you get echo only(but allways) when calling
analog phones.
You never get echo by calling GSM and ISDN.
By the way, how does all the other classic ISDN-PBX??s handle this
analog echo thing.
Does the all have also built in EC??s? Then even also every single
ISDN-Phone needs an EC,
when the phone is directly conneted via PtM?
old Equipment gets the Echo too, but the delay is so small, that you
won't recognize it. With SIP Phones you have at least 20 ms delay only
because of the standard RTP Paket Size.
Delay above 20ms is hearable by humans.
I can confirm the observations above (echo when calling an analog phone
or an ISDN-Line with a connected analog phone), never from GSM.
But I'm *also* getting echo for calls when using a locally connected
analog phone (connected via a TDM400 not via a SIP ATA) instead of a SIP
phone, but I'm using call-by-call providers, maybe these are introducing
an additional delay above 20ms.
zaptel has a buffersize around 16ms adding some buffer of 8-16 ms from
mISDN makes Echo hearable again, that's a general fact in multi
technologie environments like asterisk.
Ralf
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