GSM noise in speakers even when phone is not receiving SMS..

Archived from groups: alt.cellular.gsm (More info?)

As most GSM users know, you can tell that a GSM phone is sometimes
transmitting data, if it lies next to a speaker or headphone. For
example when the phone receives an SMS, or when you travel and the
phone changes to a different transmitter station.

My question is: Why is it that GSM phones sometimes transmit data,
even when the phone does not receive an SMS or changes the transmitter
phone?

If this happens for no apparent reason, could it be interpreted as a
clear sign that the phone is being "homed" or positioned, for example
by the police?

Or are some carrier networks simply programmed to, on a regular basis,
check up with the phone if it's still turned on?
(If it's relevant, my carrier network is Vodafone of Sweden. (If you
wonder wny I don't ask them directly, well it's because their customer
support department never respond to the email that I send them, for
some funny reason))

Please email me a copy of any replies. Thank you!

Archived from groups: alt.cellular.gsm (More info?)

On 4 Feb 2005 03:22:42 -0800, makterna@hotpop.com (Makterna) wrote:

>My question is: Why is it that GSM phones sometimes transmit data,
>even when the phone does not receive an SMS or changes the transmitter
>phone?

See http://ccnga.uwaterloo.ca/~jscouri [...] t.html#4.6

"For reliability reasons, GSM also has a periodic location updating
procedure. If an HLR or MSC/VLR fails, to have each mobile register
simultaneously to bring the database up to date would cause
overloading. Therefore, the database is updated as location updating
events occur. The enabling of periodic updating, and the time period
between periodic updates, is controlled by the operator, and is a
trade-off between signalling traffic and speed of recovery. If a
mobile does not register after the updating time period, it is
deregistered.

"A procedure related to location updating is the IMSI attach and
detach. A detach lets the network know that the mobile station is
unreachable, and avoids having to needlessly allocate channels and
send paging messages. An attach is similar to a location update, and
informs the system that the mobile is reachable again. The activation
of IMSI attach/detach is up to the operator on an individual cell
basis."

As I understand it, the network is checking if the phone is still
switched on and in range of a cell.

--

Regards

John Riggs

Archived from groups: alt.cellular.gsm (More info?)

My T-Mobile USA phone "checks in" precisely every 30 minutes.

--

\/ L /\ D


"matt weber" <mattheww50@cox.net> wrote in message
news95801d1o2hdc6b3sito5agfrn9qlipaho@4ax.com...
On 4 Feb 2005 03:22:42 -0800, makterna@hotpop.com (Makterna) wrote:

Operators of GSM networks 'poll' phones at some interval. I have seen it as
often as every 4 hours or so, or as rarely as once a day.