<html><div style='background-color:'><DIV class=RTE><FONT style="FONT-SIZE: 11px; FONT-FAMILY: tahoma,sans-serif">(Previous reply got garbled in Hotmail)</FONT></DIV>
<DIV class=RTE><FONT style="FONT-SIZE: 11px; FONT-FAMILY: tahoma,sans-serif">From: <I>"Trevor G. Hammonds" <trevor@concipient.net></I><BR>Date: <I>Wed, 7 Feb 2007 04:49:08 -0800</I><BR>> > From: Yuan LIU<BR>> > Sent: Tuesday, February 06, 2007 8:11 PM<BR>> ><BR>> > After reading through several recent threads, I started to wonder why the<BR>> > Cisco document (and other VoIP documents) appears to present this issue as<BR>> > VoIP gateway specific. Don't (plain old) PBX' face the same issue if they<BR>> > use analogue interfaces? If there are analogue PBX' at all, how do they<BR>> > solve the problem?<BR>><BR>>Yuan,<BR>>Well engineered analogue PBXs typically do not use standard loop start<BR>>subscriber lines. When digital trunks are not an option, they use
analogue<BR>>PBX and/or DID trunks. At the very least, ground start circuits are<BR>>preferred to avoid "glare". The best call quality for analogue is achieved<BR>>by using four-wire E&M trunks that provide answer and disconnect<BR>>supervision. There are two-wire trunks (which are probably more common), as<BR>>well as different signalling methods. These trunks require special<BR>>interface hardware, and I am unaware of any that work with Asterisk. As the<BR>>cards are typically very expensive, it is usually better to go with digital<BR>>if you require that functionality. It would be nice to see a BRI interface<BR>>for Asterisk that works in North America, as BRI circuits are often<BR>>comparable in price to analogue lines.<BR></DIV></FONT>
<DIV class=RTE><FONT style="FONT-SIZE: 11px; FONT-FAMILY: tahoma,sans-serif">Thanks for enlightenment, Trevor. I always thought Eicon and other standard BRI cards work with Asterisk?</FONT></DIV>
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<DIV class=RTE>Yuan Liu</DIV>
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<DIV class=RTE><FONT style="FONT-SIZE: 11px; FONT-FAMILY: tahoma,sans-serif">> Sincerely,<BR>> Trevor Hammonds<BR></DIV></FONT></div></html>