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