New CO , Mitel SX200 ground start problems

BOB · Joined: 21 Feb 2008 Posts: 6

Recently our local CO installed a new switch. Now we are having
problems with our Mitel SX-200
ground start lines. Seems the SX-200 doesnt hold the ground start long
enough for the new CO to
recognize a call for dial tone. The SX-200 will pull a dial tone
about 30 percent of the time. I dont
see that the ground start timing is variable on the Mitel SX-200. I
hope the CO can make some
sort of accomodation. Anybody run into this kind of a problem on some
of the newer CO switches
they are installing around the country Id appreciate hearing what you
were able to do about it.
Bry

Archived from group: comp>dcom>telecom>tech

DTC · Joined: 03 Nov 2007 Posts: 234

BOB wrote:
> Recently our local CO installed a new switch. Now we are having
> problems with our Mitel SX-200
> ground start lines.

Try http://tinyurl.com/32cfde that points to:

http://www.sundance-communications.com/cgi-bin/ultimatebb.cgi?/ubb/forum/f/6.html

Rich Piehl · Joined: 25 Jul 2007 Posts: 40

BOB wrote:
> Recently our local CO installed a new switch. Now we are having
> problems with our Mitel SX-200
> ground start lines. Seems the SX-200 doesnt hold the ground start long
> enough for the new CO to
> recognize a call for dial tone. The SX-200 will pull a dial tone
> about 30 percent of the time. I dont
> see that the ground start timing is variable on the Mitel SX-200. I
> hope the CO can make some
> sort of accomodation. Anybody run into this kind of a problem on some
> of the newer CO switches
> they are installing around the country Id appreciate hearing what you
> were able to do about it.
> Bry

Asking the obvious (because I've seen it before) are you sure when they
replaced the switch all your ground start lines are still ground start
and loop start lines for extraneous devices are still loop start. I've
seen the telcos or clec bolix it up on those kinds of switches on more
than one occasion.

Take care,
Rich

God bless the USA

--
That's one of the problems in this country
The nuts don't know they're nuts.

--Jeff Foxworthy

BOB · Joined: 21 Feb 2008 Posts: 6

Thanks Rich,
Yes, I checked that. they are ground start and they will start
manually but they need a good seems like a half second to ground in
order to start. Thought current was a little low. Barely 20 ma start
current and 15ma line current @ 7.9 volts when dial tone is
established. Don't know
what normal values should be. I never checked these parameters on the
old CO. Im told the new
CO is an EMS? Lucent Technologies Switch.

>
> Asking the obvious (because I've seen it before) are you sure when they
> replaced the switch all your ground start lines are still ground start
> and loop start lines for extraneous devices are still loop start. I've
> seen the telcos or clec bolix it up on those kinds of switches on more
> than one occasion.
>
> Take care,
> Rich
>
> God bless the USA
>
> --
> That's one of the problems in this country
> The nuts don't know they're nuts.
>
> --Jeff Foxworthy

Rich Piehl · Joined: 25 Jul 2007 Posts: 40

BOB wrote:
> Thanks Rich,
> Yes, I checked that. they are ground start and they will start
> manually but they need a good seems like a half second to ground in
> order to start. Thought current was a little low. Barely 20 ma start
> current and 15ma line current @ 7.9 volts when dial tone is
> established. Don't know
> what normal values should be. I never checked these parameters on the
> old CO. Im told the new
> CO is an EMS? Lucent Technologies Switch.

DMS 100, perhaps? Those values are a little low - are you a long way
from the switch?

I take it you have no timers om the Mitel to adjust the duration of the
grounding? I'm not a Mitel person, but the larger switches I do know
have an adjustment for that. Or have you played with all those till
you're sick of 'em?

Take care,
Rich

God bless the USA

--
That's one of the problems in this country
The nuts don't know they're nuts.

--Jeff Foxworthy

Bill · Joined: 25 Jul 2007 Posts: 2

Rich Piehl wrote in
$rA2.126@newsfe06.lga:

> BOB wrote:
>> Thanks Rich,
>> Yes, I checked that. they are ground start and they will start
>> manually but they need a good seems like a half second to ground in
>> order to start. Thought current was a little low. Barely 20 ma start
>> current and 15ma line current @ 7.9 volts when dial tone is
>> established. Don't know
>> what normal values should be. I never checked these parameters on the
>> old CO. Im told the new
>> CO is an EMS? Lucent Technologies Switch.
>
> DMS 100, perhaps? Those values are a little low - are you a long way
> from the switch?
>
> I take it you have no timers om the Mitel to adjust the duration of the
> grounding? I'm not a Mitel person, but the larger switches I do know
> have an adjustment for that. Or have you played with all those till
> you're sick of 'em?
>
> Take care,
> Rich
>
> God bless the USA
>
>

Bob.

On some digital end office switches, such as the Lucent 5ESS, a software
driven line parameter in the CO switch may need to be set to insure that it
recogizes your PBX momentary grounded ring side conductor to convert the
line to loop start operation (Tip ground returned by CO) and draw dialtone.

For example, in the Lucent 5E a line paramter of Ground Reference set to
"Yes" value if the 5E line card is connected to a Digital Loop Carrier
channel unit (AKA: SLC) to reach a customer location. This feature
overcomes the 5E's floating ground power plant. I do not know of the
equivalent to the NTI DMS100 switch.

DMS100 guru's please provide any comments.

Second item, Check you PBX -48VDC power plant to insure that it is
connected to a solid ground source. The ground found on commercial 110VAC
electrical outlets are not suitable for medium to large scale business
telecom installations.

REF: ANSI T1.401, & GR-506-CORE, Issue 1.

Bill

BOB · Joined: 21 Feb 2008 Posts: 6

Rich Piehl wrote:
> BOB wrote:
> > Thanks Rich,
> > Yes, I checked that. they are ground start and they will start
> > manually but they need a good seems like a half second to ground in
>
> I take it you have no timers om the Mitel to adjust the duration of the
> grounding? I'm not a Mitel person, but the larger switches I do know
> have an adjustment for that. Or have you played with all those till
> you're sick of 'em?
>
> Take care,
> Rich
>
> God bless the USA
>
Thanks Rich, Yes there are no adjustments on the Mitel for duration
adjustment. And yes, we played around with any and all of the other
adjustments to no avail.

BOB · Joined: 21 Feb 2008 Posts: 6

Checked the system ground to Bell Ground is less than 1 ohm.
The current value i just quoted are wrong. It was 45ma and 50 ma
rather than 15 and 20ma, so thats more like it. No the CO is less than
2 miles away so thats shouldnt be a problem. 48 volts is present. 8
volts under load. I think as you suggest the CO needs to be
programmed for a shorter duration recognition time in its software.
Theyre looking into that today. Finally I found someone who knows
something about the software aspect of this new switch at Bell. If
they cant do anything , I think we have come up with a workaround
solution using a loop start line and two trunkcard circuits in the
Mitel to obtain our objective system behavior. Since as was suggested
on the Sundance Mitel board forum/ultimatebb.php?/ubb/get_topic/f/6/t/000988.html>, a modern loop
line will ring in and disconnect itself with the trunk switch in the
"ground start position",, that takes care of the inbound traffic. So
for the outbound traffic we connect a second trunk circuit with its
trunk switch in the "loop position" and route outbound through that
connection. So we would use two trunkcard circuits on the one CO loop
line. So we now have inbound direct inward dial and outbound speeddial
using the one loop phone line . I tested it and it seems to work!!
we can cancel the ground start lines and use loop.

BOB · Joined: 21 Feb 2008 Posts: 6

Of further note, the old switch was over 10 miles away and we had no
problem drawing a diatone
with the Mitel SX200. Now this new switch, much closer, wont respond
unless you give it more than 200 ms of ground time. I think thats what
the Mitel is designed at. So as you suggest, hopefully
it can be remedied with a software change on this new switch.

ONe other glitch on this new CO switch is excessive gain. on say 15
percent of calls you get
a feedback squeeling sound that starts off minor but then grows so bad
you have to hang up and redial the call. Wonder if that is a software
setting too or a bad card somewhere.

Thankyou for your help. Ill let you know how this pans out when its
finished.

God Bless Bob

BOB · Joined: 21 Feb 2008 Posts: 6

Oh yes I forgot to mention, we have two sx200 systems at two different
locations and they are both behaving the same way with this new CO EMS
switch.

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