Cell Phone Clock Inaccuracy [Telecom]

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And all this time I thought cell phones were
networked-synched for their time-of-day displays.

For the 10 years I've carried a cell phone (two qualcomms
and now a Samsung), the time-of-day has been reliable and

That ended on Christmas eve day, when I temporarily lost my
phone, decided to get a replacement (another Samsung) and
discovered that its clock was 4-6 minutes slow. The
T-mobile store people assured me this "happened all the
time" -- some clocks were on, others were off. "That
doesn't make any sense," I said.

They shrugged. My old phone was found and returned a few
days later. I disliked the new phone for many reasons
besides the slow clock, so I took it back, reactivated my old
phone. And now it too was 4-6 minutes slow. I can travel to
different areas and compare my phone to others' with the
same carrier. They're on, I'm off.

I can manually set the clock in the phone, but within a few
moments it is  updated back to the wrong time. I went back
to the store, checked maybe 18 display phones. Three were
running 4-6 minutes slow, two were more than five hours
off, the others were accurate, far as I could tell.

So now I'm trying to understand just how this is happening,
assuming a network time sync signal, and moreover, how it
can be fixed. (T-Mobile Tech Support said they wouldn't
even consider generating a trouble ticket until "enough"
people complained.)

Any ideas?


Re: Cell Phone Clock Inaccuracy [Telecom]
Frank Stearns wrote:
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That really sounds strange, the phone is always in contact with the
switch which has a network clock, and that must be right or other
problems will be caused.  The switch clock is also updated with other
clocks. Also each time a call comes in the clock will update as all
phone do with CID. I checked all 3 of my cell phones 1 each of a Palm,
Samsung and Sanyo, all 3 have the same time, my CID box seems to be
also the same.  I checked my computer which is on a network clock and
updates every 5 minutes and also is the same, or at least the same
miute, the seconds could be off.

I know that when I had worked on CO Switches we had a cross between
the network clock and a backup and the switch would not work correctly
until we found and reversed the cables.

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Re: Cell Phone Clock Inaccuracy [Telecom]
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I know you said that you can set your clock manually in the phone but
make sure your phone is set to "Network" as opposed to "Phone" for
time source.  This seems to be only an option on GSM/GPRS phone
carriers such as T-Mobile and AT&T.  The phones you saw on display in
the store may have been set to "Phone" or "Manual", which is why they
may have been off.   The phone's time from the Network  comes from the
cell tower which is either all in sync via the MSC (switch) or via the
GPS antennas that all cell sites have.  (As an aside, some people
thing the GPS on the site is so they know where the site is....well,
the site doesn't move so they know where it is - the GPS is used for
time sync across the network).


Re: Cell Phone Clock Inaccuracy [Telecom]
Anyone has the same problem with iPhone? It seems other cellphones
have a lot of QA issues.

Re: Cell Phone Clock Inaccuracy [Telecom]
On Jan 19, 2:17 am, alex.pux...@gmail.com wrote:
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Like what the other poster suggested, try to check if you can turn
time sync off on your Iphone or any other mobile phone.

Re: Cell Phone Clock Inaccuracy [Telecom]
Stephen wrote:
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My Palm on the Sprint Network has an option to set the date and time
network to nothing.

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(c) 2009  I Kill Spammers, Inc. A Rot In Hell Co.

Re: Cell Phone Clock Inaccuracy [Telecom]

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Only CDMA (used by Verizon Wireless and Sprint PCS, for now, but not
Sprint iDEN) requires accurate time synchronization.  GSM systems,
like your T-Mobile service, work just fine with time synchronization
at the level of "whatever the MTSO technician's watch says".

A number of companies make precision timing receivers based on CDMA
technology; at the office I have an NTP stratum-1 using an EndRun
Technologies Praecis Ct (no longer sold) with good results.  (The
server currently reports an offset for that source of 50 microseconds
with jitter of 15 microseconds, which is not bad considering that the
server and the timecode generator both have uncompensated quartz
crystal oscillators.)

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Opinions not those   | grants to rare events of meanness such power to shape
of MIT or CSAIL.     | our history. - S.J. Gould, Ten Thousand Acts of Kindness

Re: Cell Phone Clock Inaccuracy [Telecom]
Frank Stearns wrote:
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That means it is not the phone itself.  The cell system is sending
wrong time settings to your phone.

See if there is an option in the phone's setup menus that will turn
off the network's ability to change the time on your phone.  This
should cure the problem (up to the accuracy limit of the clock in the
phone itself, and you can set that manually every month or so if the
need arises).

This will also eliminate the annoying behavior where your phone will
silently reset its clock when you cross a time zone boundary (and
sometimes get the boundary wrong, thus leaving you wondering which
time zone it is really giving you) -- a problem I've found especially
vexing in the Rocky Mountain states where coverage is sparse anyway.

Re: Cell Phone Clock Inaccuracy [Telecom]

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This is one of the first things I tried to check: went to a friend who is 14
away and also on T-mobile. Surely I was sync'd to his local tower. Powered my
on/off - my time was still wrong, his was right.

Leads me to believe the phone is wrong, but the mechanism is unclear. Does the
have to do some sort of time calculation based on a raw time signal? Perhaps
something akin to a UNIX computer's clock based on a 32-bit number counting
microseconds from 1970 or some such -- the display time of day is derived from
value. (As an aside there'll be a Y2K-like rollover issue with UNIX boxes in
or something like that, IIRC.)

If so, seems odd unless there was a "failure in the silicon" inside my phone
that some intermediate place value in a CPU register (or perhaps the firmware
holding some time calculation constant) is now stuck on or off, or has the wrong
value, and this means there's always this 4-6 minute error.

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I did find the manual setting with no updating; thanks to the poster who gave
details on this. That helps; I'll find out how much the phone time drifts.

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This actually worked for me reasonably well this past September during a
crossing road trip. But I can see how this could get iffy if crossing times
zones a

Thanks to all who had suggestions on this issue.


Re: Cell Phone Clock Inaccuracy [Telecom]
On Fri, 16 Jan 2009 20:59:05 -0500, Frank Stearns  

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[Moerator snip]

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All  I can tell you, Frank, is that my T-Mobile-supplied
Nokia 6610 has a setting "Auto-update of date & time" with
options "On", "Confirm first", and "Off".

You reach it by selecting, in turn, "Menu", "Settings",
"Time and date settings", and "Auto-update of date & time".

I run with the "On" option. Whenever the local time changes
(EST/DST changeover, or I'm in a new timezone), it's not long
before that Nokia reflects the new time, which seems to be
about as accurate as the carrier handling me cares to make it.

Same thing, more or less, for my wife's T-Mobile Moto RAZR V3.

Hope this has helped at least a little. Cheers,

-- tlvp

Re: Cell Phone Clock Inaccuracy [Telecom]
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My T-Mobile Moto RAZR V3 has settings under "Settings | Initial
Settings | Time and Date" of "Autoupdate", which can be set On or
Off.  (I don't see a "Confirm first" setting.)  If you set it to
"Off" options to manually set the time and date appear.

I tried setting the time off by 5 minutes, then switching it back
to autoupdate.  The time got switched back immediately.

I've checked the time occasionally and it seems to be pretty close
to my NTP-synchronized computer, but since the phone doesn't display
seconds it's hard to be sure.  I haven't crossed time zones with
the phone yet so I don't know what happens then.  Something a little
funny happened at one of the DST transitions.  I think the transition
happened half an hour off or so (I don't remember whether it was
early or late) but it transitioned in one jump.

If I was having trouble with the time jumping around between time
zones, say, travelling at an airport on a time zone boundary (does
that happen at any actual airport?  I do seem to remember being at
one airport which was divided down the middle by an area code
boundary, and your cost for calls varied a lot based on the area
code of the pay phone.  That was a couple decades ago.), it looks
like I could set it to manual fairly easily and stop that from
happening, provided I realized it was an issue.

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