[asterisk-users] OT - Incoming fax cuts ADSL line
Hi, I'm facing a strange situation. Though it's not directly related to Asterisk, I do think it is interesting to this mailing list. The setup is a single line which is split between an ADSL modem/routeur and a fax machine (Asterisk was removed from the equation). Any time the fax machine rings (incoming fax), the ADSL service is troubled to the VPN users are disconnected. It can be reproduced at will. I've changed the ADSL filter twice (a different unit, then a different model) without any visible change. What could explain this ? Regards -- _ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] OT - Incoming fax cuts ADSL line
- Original Message - Hi, I'm facing a strange situation. Though it's not directly related to Asterisk, I do think it is interesting to this mailing list. The setup is a single line which is split between an ADSL modem/routeur and a fax machine (Asterisk was removed from the equation). Any time the fax machine rings (incoming fax), the ADSL service is troubled to the VPN users are disconnected. It can be reproduced at will. I've changed the ADSL filter twice (a different unit, then a different model) without any visible change. What could explain this ? I've experienced this quite a few times, and after working with a local telco, it has become policy to not place ADSL on lines where fax is going to be used. I'm unsure of the exact technical reasons behind this other than 'the fax signals/frequencies interfere with the ADSL signalling/frequencies used on the circuit'. It sounds like you might want to separate your fax/ADSL lines. --Tim -- _ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] OT - Incoming fax cuts ADSL line
I've experienced this quite a few times, and after working with a local telco, it has become policy to not place ADSL on lines where fax is going to be used I too have seen this, and also with credit card processing machines in shops that 'dial' the merchant bank to process transactions (in effect a modem). It can sometimes (but not always) be resolved by running two microfilters in series on the 'voice' side of the line, i.e. line - microfilter - microfilter - fax. I've also (here in the UK) seen it resolved through the use of higher quality faceplate splitters rather than the often low-cost units supplied free with consumer ADSL modem/routers. Kind regards, Chris -- This email is made from 100% recycled electrons -- _ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] OT - Incoming fax cuts ADSL line
On 5/16/2012 12:07 PM, Tim Nelson wrote: - Original Message - Hi, I'm facing a strange situation. Though it's not directly related to Asterisk, I do think it is interesting to this mailing list. The setup is a single line which is split between an ADSL modem/routeur and a fax machine (Asterisk was removed from the equation). Any time the fax machine rings (incoming fax), the ADSL service is troubled to the VPN users are disconnected. It can be reproduced at will. I've changed the ADSL filter twice (a different unit, then a different model) without any visible change. What could explain this ? I've experienced this quite a few times, and after working with a local telco, it has become policy to not place ADSL on lines where fax is going to be used. I'm unsure of the exact technical reasons behind this other than 'the fax signals/frequencies interfere with the ADSL signalling/frequencies used on the circuit'. It sounds like you might want to separate your fax/ADSL lines. --Tim You might also be able to limit the Fax machines maximum transmission rate so the modem's transmission spectrum doesn't inch up into where the ADSL service is. -- _ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] OT - Incoming fax cuts ADSL line
-Original Message- From: asterisk-users-boun...@lists.digium.com [mailto:asterisk-users-boun...@lists.digium.com] On Behalf Of James Sharp Sent: Wednesday, May 16, 2012 11:19 AM To: Asterisk Users Mailing List - Non-Commercial Discussion Subject: Re: [asterisk-users] OT - Incoming fax cuts ADSL line On 5/16/2012 12:07 PM, Tim Nelson wrote: - Original Message - Hi, I'm facing a strange situation. Though it's not directly related to Asterisk, I do think it is interesting to this mailing list. The setup is a single line which is split between an ADSL modem/routeur and a fax machine (Asterisk was removed from the equation). Any time the fax machine rings (incoming fax), the ADSL service is troubled to the VPN users are disconnected. It can be reproduced at will. I've changed the ADSL filter twice (a different unit, then a different model) without any visible change. What could explain this ? I've experienced this quite a few times, and after working with a local telco, it has become policy to not place ADSL on lines where fax is going to be used. I'm unsure of the exact technical reasons behind this other than 'the fax signals/frequencies interfere with the ADSL signalling/frequencies used on the circuit'. It sounds like you might want to separate your fax/ADSL lines. --Tim You might also be able to limit the Fax machines maximum transmission rate so the modem's transmission spectrum doesn't inch up into where the ADSL service is. ADSL is transmitted at a relatively low frequency using phase modulated carriers to achieve the bandwidth. It could be about 32 different phase/level locations on 360 degree/level pie chart or vector scope. The actual frequencies of the carrier are moderately low, maybe 100 to 200 kcps. Voice is low density. Faxes and modems are high density and loud. They can splatter or have harmonics that can confuse the local DSL demodulator. As others have said, the best thing to try is the best filters you can get between the phone line and the DSL demod, and maybe two filters in series. If that doesn't work, put the fax on a different line than the DSL, which could cost you money. Paying for better filters or two of them is less expensive than separate lines. Or move the DSL to an alternate existing voice only line, since you probably don't want to change the fax number Contents of this message were dredged from foggy memory. Cary Fitch -- _ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] OT - Incoming fax cuts ADSL line
On 17/05/2012 12:18 AM, James Sharp wrote: On 5/16/2012 12:07 PM, Tim Nelson wrote: - Original Message - Hi, I'm facing a strange situation. Though it's not directly related to Asterisk, I do think it is interesting to this mailing list. The setup is a single line which is split between an ADSL modem/routeur and a fax machine (Asterisk was removed from the equation). Any time the fax machine rings (incoming fax), the ADSL service is troubled to the VPN users are disconnected. It can be reproduced at will. I've changed the ADSL filter twice (a different unit, then a different model) without any visible change. What could explain this ? I've experienced this quite a few times, and after working with a local telco, it has become policy to not place ADSL on lines where fax is going to be used. I'm unsure of the exact technical reasons behind this other than 'the fax signals/frequencies interfere with the ADSL signalling/frequencies used on the circuit'. It sounds like you might want to separate your fax/ADSL lines. --Tim You might also be able to limit the Fax machines maximum transmission rate so the modem's transmission spectrum doesn't inch up into where the ADSL service is. I have clients with their ADSL2+ service attached to their fax lines with no problems observed. Perhaps the issue is the fax machines attenuators are not set correctly are are to _loud_ on the PSTN. In Australia Telstra advised the signal level received at the exchange should be between -15dB and -17dB. They have a Fax On Line Diagnostic System (FOLDS) which you can send a transmission to, a report is returned advising of the quality of your transmission including measured signal and noise levels. In old days the fax machine might have a wired jumper block to set the attenuation, more modern devices would be configured from the front panel, typically in a maintenance mode. Your good old dial-up modems with fax capabilities would have an S-Register or two to set the attenuation. Larry. -- _ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
