Jeff Binkley ( )
Thu, 12 Jun 1997 09:54:00 -0500

Let me try and spread some light on this myth. Central office switches
would not stop hunting unless there was a problem with the switch or an
external problem which made them believe a line was onhook, when it
actually was offhook. Now the problem is further compounded by the fact
that most dialtone used for modems uses what is called loop start
singalling. A better solution, often used on PBX systems, is ground
start singalling. Ground start has a 2 phase off hook sequence and can
reduce signalling contention, especially on two way circuits (i.e. used
both inbound and outbound). This is called a glare condition and ground
start has provisions for this as well as making sure an offhook is
really an offhok.

So what does this mean for us with loopstart lines and modems ? If you
believe the problem is external, which is a likely cause, then loop
current becomes a prime candidate for the problem. The way to measure
loop current is to stick a volt-ohm-meter across the line and set it on
the 200ma scale to measure current. Normal lines will measure something
along the line of 35ma but a range of 25ma up to 50ma is possible.
Outside of this range indicates you most likely have a cable problem.
This is a good place to start. I can go further if this doesn't help.

Jeff Binkley
ASA Network Computing

N>I read in a different group about the same problem. It is a problem
N>with the hunt set up on your telecom. For some reason analog lines
N>will sometime fail to hunt and give a constant ring. If it was a
N>modem problem, the circuit hunt should bypass the modem after a set
N>number of rings.

N>Sent: Wednesday, June 11, 1997 4:47 PM
N>Subject: Modem not answering....

N>List Members:

N>I have recently discovered a sporadic problem that I am in the process
N>of troubleshooting. That is why I am soliciting all of your

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