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tnelson at rockbochs.com
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 Posted: Wed Jan 09, 2008 10:15 am Post subject: [asterisk-users] Zaptel FXS Cards - Station Distance |
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Hello! In the near future, I'll be deploying an asterisk system that will have (in addition to many SIP handsets) four FXS handsets. Is there a known limitation to the length of cabling that can be used between a Digium/Openvox/Sangoma FXS card and the end station? I understand the card will need a molex power connector plugged in to provide extra voltage. With traditional phone systems, I have not seen any distance limitations. I would just like to verify that the FXS ports are able to provide sufficient power for longer runs. Thank you!!!
Tim Nelson
Systems/Network Support
Rockbochs Inc. |
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kpfleming at digium.com
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| Posted: Wed Jan 09, 2008 10:47 am Post subject: [asterisk-users] Zaptel FXS Cards - Station Distance |
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Tim Nelson wrote:
| Quote: | Hello! In the near future, I'll be deploying an asterisk system that will have (in addition to many SIP handsets) four FXS handsets. Is there a known limitation to the length of cabling that can be used between a Digium/Openvox/Sangoma FXS card and the end station? I understand the card will need a molex power connector plugged in to provide extra voltage. With traditional phone systems, I have not seen any distance limitations. I would just like to verify that the FXS ports are able to provide sufficient power for longer runs. Thank you!!!
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You don't quote any numbers here, and 'longer' is not anything we can
relate to.
However, I can say that the FXS line drivers on Digium analog modules
should be able to handle 1000' runs or so, but not more than that. This
should be equivalent to what any standard PBX with FXS ports can do,
unless it has special 'long line' drivers.
--
Kevin P. Fleming
Director of Software Technologies
Digium, Inc. - "The Genuine Asterisk Experience" (TM) |
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tilghman at mail.jeffa...
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| Posted: Wed Jan 09, 2008 10:49 am Post subject: [asterisk-users] Zaptel FXS Cards - Station Distance |
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On Wednesday 09 January 2008 09:15:08 Tim Nelson wrote:
| Quote: | Hello! In the near future, I'll be deploying an asterisk system that will
have (in addition to many SIP handsets) four FXS handsets. Is there a known
limitation to the length of cabling that can be used between a
Digium/Openvox/Sangoma FXS card and the end station? I understand the card
will need a molex power connector plugged in to provide extra voltage. With
traditional phone systems, I have not seen any distance limitations. I
would just like to verify that the FXS ports are able to provide sufficient
power for longer runs. Thank you!!!
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There are limitations, even with traditional systems. It's usually around
1,000 feet, but the basic problem is that DC signalling degrades over
distance. Incidentally, this is why power lines are provided with AC current.
The TDM cards should be able to provide reliable signalling over the same
distance as traditional telephony lines, as they are sending with the same
power specifications.
--
Tilghman |
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jnovack at stromberg-c...
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| Posted: Wed Jan 09, 2008 11:44 am Post subject: [asterisk-users] Zaptel FXS Cards - Station Distance |
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Kevin P. Fleming wrote:
| Quote: | Tim Nelson wrote:
| Quote: | Hello! In the near future, I'll be deploying an asterisk system that will have (in addition to many SIP handsets) four FXS handsets. Is there a known limitation to the length of cabling that can be used between a Digium/Openvox/Sangoma FXS card and the end station? I understand the card will need a molex power connector plugged in to provide extra voltage. With traditional phone systems, I have not seen any distance limitations. I would just like to verify that the FXS ports are able to provide sufficient power for longer runs. Thank you!!!
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You don't quote any numbers here, and 'longer' is not anything we can
relate to.
However, I can say that the FXS line drivers on Digium analog modules
should be able to handle 1000' runs or so, but not more than that. This
should be equivalent to what any standard PBX with FXS ports can do,
unless it has special 'long line' drivers.
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In reality many PBX analog circuits using DTMF only can go quite a bit
longer. The 1K foot limitation with pulse dial is more realistic, due
to cable capacitance mis shaping of pulses. DTMF only is limited by the
line resistance limiting current to 20-30 Ma required to operate the
tone pad. More modern ( cheap Chinese ) phones often will operate with less.
With lower than normal 48VDC supplies, the distance grows ever shorter.
So, what is the distance you require?
What is the size of the wire in the cable?
Dial long line circuits ARE available, and advised along with special
protection if the stations will be off premises.
John Novack
--
Dog is my co-pilot |
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