No ring in remote area - Motorola 3watt bag phone.

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pjwlk - 29 Jan 2004 06:46 GMT

I'm trying to figure out what is causing my Motorola bag phone not to
ringing when I'm in a remote location even though I have good signal
strength. Here's the details:

- The phone is a Motorola 3 watt analog Bag Phone, Series II (I
think). It has only the RCL and FCN keys. The handset type is
SCN2497B.

- The phone is located in a remote location in South-Central Ontario
about 30-40 Km away from the tower.

- The phone is hooked up to a Yagi analog-range cell phone antenna
which is mounted on a 25' pole for better reception.

- The signal strength is about 3/4 of full and the phone calls out and
sounds great. The signal strength is less with the original flexible
antenna.

- The phone does NOT ring when somebody calls, but the LCD display
lights up. The display does not show "Call" as it would normally when
the phone rings.

- The phone will ring if I use the original flexible antenna and I
take it to a location further south and call it with my digital cell.

_______________________________________________

I figure this may be a problem with the phone being in a low power
mode when the cell system is looking to see if the phone is active and
can't find it. I'd really like to try and force the phone to stay in
high power mode if possible to see if this is the problem. Any help
would be greatly appreciated. - Thanks in advance.

Paul

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N9WOS - 29 Jan 2004 18:54 GMT

> - The phone is located in a remote location in South-Central Ontario
> about 30-40 Km away from the tower.
[quoted text clipped - 9 lines]
> lights up. The display does not show "Call" as it would normally when
> the phone rings.

Question....
Does your bag phone support caller ID?
If it doesn't, it can sometimes cause varied results.
If it does not, then make sure they have call ID disabled for your account.

> - The phone will ring if I use the original flexible antenna and I
> take it to a location further south and call it with my digital cell.

Another question.
Is it the same tower you are connecting to?
You may be connecting to a competitor's tower with the yagi,
and the system isn't allowing the call to go through.

> I figure this may be a problem with the phone being in a low power
> mode when the cell system is looking to see if the phone is active and
> can't find it. I'd really like to try and force the phone to stay in
> high power mode if possible to see if this is the problem. Any help
> would be greatly appreciated. - Thanks in advance.

The power settings should not bother it.
The only other thing I can think of is the beam pattern may be
covering more than one cell site, and the system can't
figure out where to direct your call.

Reply to this Message

pjwlk - 02 Feb 2004 17:43 GMT

You've got some good points here, and they raise more questions.
---------------------------

> Question....
> Does your bag phone support caller ID?
> If it doesn't, it can sometimes cause varied results.
> If it does not, then make sure they have call ID disabled for your account.

---------------------------

The phone does not support caller ID. I didn't thing CID was a part
of the analog cell systems. If it is, isn't CID sent between the
first and second rings or is that just for land lines? How do you feel
CID could effect the phone in this case.

---------------------------

> Another question.
> Is it the same tower you are connecting to?
> You may be connecting to a competitor's tower with the yagi,
> and the system isn't allowing the call to go through.

---------------------------

Good point about the Yagi. However, the same thing happens if I just
use the bag phone's regular OEM (omni-directional) flex antenna at the
remote location instead of the Yagi, the signal is just weaker. As an
additional note, it appears that I can receive from three different
towers with the yagi. The closest tower geographically does not yeild
the best signal and I have not tried the other towers for a ring.
Also, curiously, my home phone long distance bill sometimes shows the
remote phone as calling from Sudbury which is a hell of a long way
from the Northern reaches of the Haliburton region.
---------------------------

> > I figure this may be a problem with the phone being in a low power
> > mode when the cell system is looking to see if the phone is active and
[quoted text clipped - 6 lines]
> covering more than one cell site, and the system can't
> figure out where to direct your call.

---------------------------

I was thinking that the tower must be sending something out from at
least one tower or the LCD display wouldn't light up when someone
calls. Exact the same thing happens with the OEM antenna attached
directly to the phone. Doesn't the beam pattern typically cross over
cells occasionally with the OEM antenna anyway and the system decides
which cell tower to use based on the signal strength?

Thanks again in advance for your input,

Reply to this Message

CharlesH - 02 Feb 2004 18:55 GMT

>You've got some good points here, and they raise more questions.
>---------------------------
[quoted text clipped - 10 lines]
>first and second rings or is that just for land lines? How do you feel
>CID could effect the phone in this case.

With cellular, the CID is sent as part of the call setup protocol. An
extension to the AMPS protocol allows CID (and even SMS messages) to
be sent over these control commands, but phones not prepared to see
these extensions may consider them to be corrupted data and reject the
call setup. Other phones which don't support CID may just ignore the
unexpected stuff.

BTW, the ringing you hear in the cell phone is locally generated by the
phone (and thus all those cutesy ringtones which seem to be so popular).

Reply to this Message

N9WOS - 02 Feb 2004 19:22 GMT

> The phone does not support caller ID. I didn't thing CID was a part
> of the analog cell systems.

When AMPS came out, it did not have CID.
But the AMPS standard is has a bit of expandability.
They integrated CID into the system a good long time ago.
It is up to the AMPS carrier if they want to support CID or not.
All the ones I know of in the states do support it.
And from what I hear, most of them in Canada do.
Same as the fact that AMPS also supports SMS
if the carrier wants to implement it.
Most newer analog only phones support CID,
and some older ones do. (flip phones and other hand held phones)
And all digital phones with analog capability support CID in analog
operation.

> If it is, isn't CID sent between the
> first and second rings or is that just for land lines?

Cellular phones don't work like landline phones.
The tower just sends gets in contact with the phone
and tells it that someone is calling, and the details.
(ie)CID...... on an on..
The phone is what initiates the ringing (not the tower).
The tower doesn't send a ringing signal to the phone.
The phone is still on the control/paging channel at that time.
When the user hits the send button, then the phone tells
the tower that the user has accepted, then the tower
sends it to an appropriate channel to carry out the conversation.

> How do you feel CID could effect the phone in this case.

CID is an extended function.
It wasn't anticipated in some cellular phone firmware.
Companies that anticipated the extended features in the
AMPS control cannel being used, just had the phone
ignore the fields that contained that information.
Some that didn't anticipate it though.
When the phone sees data in the control signal where
there should be a "NULL"(No data){extended field}
then it interprets it as a corrupted signal, and ignores it,
or request a resend.

If it request a resend, then all resend attempts will also be corrupted.
And it finally gives up after a while.
And since it never got a "valid" call request, it never rings.
That is why it would light up when the tower is talking to it,
but then go back to standby after it gives up.

I have two moto analog bag phones that never have had a problem
with the CID even thought they are not CID capable.
(But they had their firmware update a few times by the
original owners, so that may have taken care of the CID problem.)

But I have seen a few on the news groups that have
had nokias that have had problems
and exhibited the same side effects you commented on.
They had to have CID disabled on their plan.

> Good point about the Yagi. However, the same thing happens if I just
> use the bag phone's regular OEM (omni-directional) flex antenna at the
> remote location instead of the Yagi, the signal is just weaker. As an
> additional note, it appears that I can receive from three different
> towers with the yagi. The closest tower geographically does not yeild
> the best signal and I have not tried the other towers for a ring.

The reason I ask is because they may not have the CID capability
installed on all the towers.
The one it is working on may be an older tower they have not upgraded CID.
Try the other towers and see what happens.

> Also, curiously, my home phone long distance bill sometimes shows the
> remote phone as calling from Sudbury which is a hell of a long way
> from the Northern reaches of the Haliburton region.

If you are on a hill, and you have a clear shot of that place,
then it wouldn't be surprising to do odd things when you got a high gain
yagi.
That could be a reason why the phone is acting funny.
The system sees the phone on a couple towers close to you,
and it sees it clear out in "heck knows where", and it can't figure out
which tower to handle the conversation on.
And it may be picking the wrong one.
Or you may be picking up a competitor's tower and the
system isn't letting the call go through because of roaming restrictions.

> I was thinking that the tower must be sending something out from at
> least one tower or the LCD display wouldn't light up when someone
> calls.

Yes, that is 100% correct, but the call handling is being messed up
somewhere after that.

> Exact the same thing happens with the OEM antenna attached
> directly to the phone. Doesn't the beam pattern typically cross over
> cells occasionally with the OEM antenna anyway and the system decides
> which cell tower to use based on the signal strength?

It would depend upon the people that wrote the software for the cellular
system.
It may be location based, or signal strength based, or a combination of
that.
If you are in a hilly area, then things can get strange.
If you point the antenna at other towers, the system may be able
figure out what to do.

Reply to this Message

pjwlk - 03 Feb 2004 04:04 GMT

Hey thanks again N9WOS for your insight into this problem. I'm going
to take your advise on a couple of items, and have the cell company
inhibit the CID just incase. I will also try the other towers to see
if I can get a ring. The cell company offered to look at the problem
but I have to call them from a land line so they can work on the cell
phone while talking to me on the land line. I can't take the yagi to
the closest pay phone but I should be able to receive just enough of a
signal using the OEM antenna. Hopefully it will be a staring point to
rule out a few things.

I'm just starting to learn how the system works so please forgive me
for my ignorance on this subject. I was thinking that if my phone is
having difficulty with the CID data, that it would have the same
trouble regardless of its distance or location. The fact that it
rings reliably when at another location would seem to suggest that the
CID may not be the problem.

I'm also wondering if the yagi is really even in the equation at this
point becuase the phone does not ring with or without it when at the
remote location. The yagi gain is about 10 or 11 db minus the 40 feet
or so of RG8X cable I'm using which I'm told will cut the gain in half
roughly at that frequency. You've got one thing right though, I'm at
a very high elevation and it is also very hilly. The point that I
take the phone to where it will ring with the OEM antenna is
consideralby lower and closer two of the towers. I do not have a
line of sight to any of the towers at either location.

A couple of weekends ago at the remote location, I was getting 80%
signal for a short period of time on a clear day - never seen that
before.

For conversation's sake the distance between Halibuton and Sudbury is
two or three hundred kilometres and I would imagine that at least one
of the towers between the two locations should pick up the call.
There must be another reason why my long distance company shows
Sudbury on the bill as the location I call from on the cell.

You mentioned the control/paging channel. How does the system
interact with the phone to tell it that a call is coming in?

Thanks

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N9WOS - 03 Feb 2004 05:11 GMT

> You mentioned the control/paging channel. How does the system
> interact with the phone to tell it that a call is coming in?

I was a bit in error.
The phone switches to a voice channel then rings.

Here is a site that describes it pretty good.

http://www.doc.ic.ac.uk/~nd/surprise_96/journal/vol2/pr4/article2.html.ootsav.465

As for as the phone ringing when it is close to a tower
and not ringing when it is far away.
I am totally perplexed by the problem.

I have told you all my ideas.

I would have more ideas if the problem was both ways.
(ie) You could not make calls, or receive calls.

That is why I think the CID may be the primary issue.
Or possibly the system can't figure out what tower to hand your call to.

The best idea I have at this point is pointing you to the Motorola Bible.
(Yes I am a broken record with it comes to the MB. Everyone needs it.)

http://www.qsl.net/n9zia/motorola.txt
http://packetstormsecurity.nl/cellular_telephony/motorola/motbible.txt
http://www.totse.com/en/phreak/cellular_phones/motbible.html

If you put your phone into test mode, you will be able to
get a lot more information about it's operation and
what towers you are connecting to.

To make the jumper, if you don't have a break out box,
take a single strand from a very thin stranded wire, and cut into a 3/8
length and bend it into a very small U,
then insert into the pin 20 and 21 holes of the connector.
(ie) jumping across them, then install the connector,
making sure the jumper stays in place.
When you turn on the phone, you should see the test mode display.

After you get that, see what control channels it is locking on to.
And don't dismiss a 200KM path.
Propagation can do strange things.
Like when I was tuning though the uhf dial,
And found a Mexican TV station, from Mexico.
And I live in Indiana!!!!!!!!!!!

And take into account that a yagi's beam pattern will change
with frequency.
And the RX and TX frequencies are 50Mhz apart.
So, just because the RX level is high, doesn't mean that
the TX radiation lob will be pointed at the tower you are aiming at.
(ie) The tower that hears your phone the loudest, may not
be the tower that your phone hears the loudest,
and it may be causing problems.
Same is possible with a rubber duck antenna in hilly areas.

If you had a nokia bag phone,
you could put it is field test mode,
and find the SID of the towers you are connecting to
Then you would know that you are connecting to your home system.

That is all the idea's I have.

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pjwlk - 04 Feb 2004 01:54 GMT

Hey, thanks again N9WOS, you've been a great help. I've printed out
the bible and will start playing around when I'm back up north in
early March. I'll report back my findings then.

Regards,
pjwlk

Reply to this Message

pjwlk - 27 Feb 2004 12:54 GMT

Well I was able to sneak up north a week early to get in my last
little bit of snowmobiling before the snow melts. I contacted the
cell phone company to see if they could help out at all and as
expected they were pretty much no help at all. I went through three
separate "Customer Service Representatives" (CSR) before I got
anywhere at all. None of them could tell me anything technical about
my call to them using the cell. They had no idea what cell I was
using or what path my call was taking. All they could do was to "put
in a trouble ticket" and call me back. So I'm back to square one.
Two of the CSRs did agree that my elevation could be a problem, but I
already know that from reading about why you shouldn't use a cell
phone from a plane.

My call was placed about 5km closer to the working zone than my usual
spot and I used the OEM flex antenna. The last CSR called my phone
and to my surprise it actually rung. I asked him what he did and he
said "nothing". The only differences between this time and the last
time I called from that location is there is less foliage on the trees
and it's colder. I asked him if he could force which ever cell the
system was using to ring my phone to always be the cell that tries to
ring the phone and he said he couldn't do that - but he could put in a
"trouble ticket". So he put in a trouble ticket.

I took the phone back to its regular remote site and had my daughter
call it from home - no ring. The antenna mast is frozen right now so
I can't adjust it to try another tower. One CSR went through all the
local areas that have service and I found out that there is an area
that is physically closer but the signal is actually weaker (from my
test last summer). I am going to try pointing to that area next
(after the mast thaws). I'll post back when I get more details.

Regards,
pjwlk

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