fcc
join:2007-07-13
| Hang up phone then DSL loses sync
New 1.5M DSL service on July 11 to replace intermittent Charter 10M/1M.
Problem is each time we hang up a telephone, the dsl loses sync. Here is an excerpt from logs:
2007/07/13 03:50:41 GMT E |DSL |HYBRID 1
2007/07/13 03:50:41 GMT E |DSL |Link up 8 US 384 DS 1536 (FAST:G.dmt)
[--- hang up the phone ---]
2007/07/13 13:34:47 GMT E |DSL |Link Down
2007/07/13 13:34:47 GMT E |DSL |State: Other bState = 0
2007/07/13 13:34:47 GMT E |DSL |State: WAITING
2007/07/13 13:34:53 GMT E |DSL |State: INITIALIZING
2007/07/13 13:35:00 GMT E |DSL |HYBRID 1
2007/07/13 13:35:00 GMT E |DSL |Link up 9 US 384 DS 1536 (FAST:G.dmt)
This is the setup, a self install with:
+ 1 microfilter on one jack with answer machine and wireless phone and
+ 1 microfilter on one traditional phone
+ 1 alarm panel that has line seizure through an RJ38x jack. No filter on this, but for testing I disconnect the alarm through the RJ38x jack. No difference either way.
Phone wiring is star config from the NID. There are two additional unterminated phone wiring runs from the NID.
I have tried to narrow down possible causes, such as each phone and the alarm panel by disconnecting them from their respective jacks. Obviously, I need at least one phone connected to duplicate the problem.
Funny thing is when I disconnect all phones and the alarm, the dsl will not sync at all ??? I don't know if this is a related symptom.
Any guesses why hanging up phone would knock us offline?
Here's some stats from the modem (4100):
To Modem To Internet
Max Allowed Speed (kbps) 1536 384
SN Margin (dB) 16.5 -
Line Attenuation (dB) 58.5 -
Loss of Signal 0 -
Loss of Frame 0 0
CRC Errors 598 7 |
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nwrickert
sand groper
Premium,MVM
join:2004-09-04
Geneva, IL
 ·AT&T U-Verse
 ·AT&T Midwest
| This FAQ might be related to your problem
»Ameritech - SBC FAQ »DSL works only with phone off-hook, known as High Open
Since your problem is very likely related to a house wiring problem, the best solution would be to install a POTS splitter at or near the NID, and run new wiring from there to where you connect your modem (usually called a home run).
--
AT&T dsl; Westell 2200 modem/router; SuSE 10.1; firefox 2.0.0.4 |
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fcc
join:2007-07-13
| Thanks for the reply. High open FAQ mentions dsl working only when phone is off hook. The problem I have is the opposite: dsl works fine when phone is on hook, then I take phone off hook and dsl continues to work fine for half a minute or until I hang up. Then dsl loses sync momentarily.
Even so, I'll try to check at NID. However, the alarm company wired their "line seizure" run by splicing at the Telco side of the NID, so I am not able to eliminate the alarm run even by using the test jack at the NID.
Guess I'll have a tech out to install a POTS splitter. |
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d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV | reply to fcc
Do you have any sync loss when your phone rings? If so, maybe you have an MTU in the NID. That possibility might be ruled out though if your NID is relatively new, say less than 6-7 years. |
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fcc
join:2007-07-13 | No, the dsl is OK when the phone rings. |
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fcc
join:2007-07-13
| Follow up: the problem was caused by a small "test board" that had been spliced in the telco side of the NID by the phone company. It's a little 1 inch by half inch pcb that's coated with weatherpoofing and the tech took it out... problem solved.
Had a splitter / homerun put in anyhow. |
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d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
1 edit | reply to fcc
That small "test board" is an MTU. I didn't think that newer NIDs (within the last 6-7 years) would have MTUs installed at the factory as they always have to be removed for DSL to work properly.
Are you still seeing the same Hybrid 1 in your modem log or has the hybrid value changed? Thanks. |
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fcc
join:2007-07-13
1 edit | Hybrid 4 now.
(BTW, d_l how do you generate those neat DMT Spectrum Charts anyhow?) |
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d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
| reply to fcc
It is a little tool coded by deblin  : »SBC DSL FAQ »How can I check for the maximum attainable sync speeds with a 5100b/4100 modem?  |
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fcc
join:2007-07-13
| 
DMT graph |
Downstream Maxrate (Estimated): 2684
Upstream Maxrate (Estimated): 690
Bit tones with notches/missing bits:
bit(s) 38:46 163.875 - 202.6875 KHz
bit(s) 72:74 310.5 - 323.4375 KHz
bit(s) 84 362.25 - 366.5625 KHz
bit(s) 109 470.0625 - 474.375 KHz
bit(s) 129:135 556.3125 - 586.5 KHz
bit(s) 141:255 608.0625 - 1104 KHz |
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d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
1 edit | reply to fcc
If you were on the 308/512 plan, you modem would never make sync because your maximum sync capability is about 2684. You would have to be capped at one of the slower maintenance profiles, most likely 1984/512.
The key sequence here is customers qualify first based on the loop length, then they get their profile adjusted to a capped speed, maintenance profile if the line won't handle full speeds.
Normally to make a go of full Pro speeds, your loop attenuation would have to be under 55.0 dB.
Edit: You can always hope that AT&T switches to the Maxsync-type profiles of the former Bellsouth region. One those, the line is run at full speed, so you might be syncing at 2684, then AT&T would throttle your download speeds to be about 2600 kbps so as to not choke the DSLAM. Now your sync speeds would vary throughout the day and the seasons, so your download throughput wouldn't be constant. Also if you had a rash of line errors, your circuit would be set to interleaved profile with its higher latency automatically. Also they only have upload speeds of 384 for the 3 mbps profile. |
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fcc
join:2007-07-13 | Thanks for the quick reply. Am I misunderstanding a difference between loop attenuation and line attenuation (from the statistics page)? Line attenuation is 48.5dB. |
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d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
1 edit | reply to fcc
I use loop attenuation and line attenuation interchangeably.
If your attenuation is now down to 48.5 dB, then you should start a PreQual thread over in AT&T Direct: »/forum/sbcdirect. Tell them you would like to upgrade to Pro speeds, but it isn't available to you at the online upgrade website or with the phone CSRs (which ever you checked) and your line attenuation is only 48.5 dB.
Originally when I interpreted your maxrate, I thought your output power would be maxed out because you had 58.5 dB attenuation (or did with the MTU and IW). Now there might be a possibility that the DMT tool is low-ball estimating your maxrate because your modem isn't running at full download output power. It may not need to because your attenuation is only 48.5 dB. This is one glaring weakness of the Speedstream modems -- no output power readings. It makes the DMT tool give low ball estimates too.
The techs in direct can remotely estimate your loop length and correct the loop length database if your distance is wrong. Also they can estimate a power level-corrected max sync rate.
Edit: Even at 48.5 dB, it won't be s sure thing qualifying for Pro. I estimate at that attenuation level your loop length would be 10.5 kft of 26 AWG Equivalent Wire Length. The qualifying distances depend on whether you are connected to an RT or CO: »Re: 6500 or 9000, That is the question.... |
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fcc
join:2007-07-13 | Excellent help from the AT&T tech in the direct forum. Checked and verified Pro should work and connected me with cs. Now getting about 2500/480 which is a nice improvement for $5 extra / mo.
Thanks for all your help. |
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d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV | reply to fcc
I'm glad that all worked out for you. How do your stats look now after the upgrade: »192.168.0.1/statistics.htm? |
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