Westermo GD-01 - Manual (Page 201)

201 6196-2220
GSM network operators, subscriptions and services
The Westermo GD-series of modems support several services in the GSM network. In
order to get the modems to work properly its important that the GSM service used in
a specific application also is enabled on the subscription (the SIM card).
When ordering a SIM card from a network operator its necessary to confirm that the
specific service needed for the application is enabled before trying to set up the commu-
nication link.
The implementations of the networks may also differ slightly from network to network.
Hints:
Some information of possible mistakes are listed below:
• When using a GSM modem in a fixed installation its in most cases a good idea to dis-
able the PIN code on the SIM card. In some GSM operators’ subscriptions its not pos-
sible to disable the PIN code.This means that every time the unit is restarted, the SIM
card wants to have the PIN code before it can register to the GSM network and work
properly. However, most of the GSM network operators allow the user to disable the
PIN code and the SIM card security is in most cases sufficient when the unit is installed
in a restricted and locked area.
• When using the CSD service its important to confirm with the operator that the serv-
ice is enabled and also the maximum speed supported by the network. Some networks
do not support all the data rates supported by the modem.
• When using the GSM modem in another GSM operators network its important to
check the roaming agreements between the “home” network operator (the operator
that provided the SIM card) and the other network operator.
• The coverage area of a specific network may not be sufficient for a reliable connection
on a specific place of installation. Several network operators may cover the same area
and it could be a good idea to contact other operators to see which network opera-
tor that provide the best GSM signal strength.
• When using a GSM modem in a fixed location, the network could be equipped with a
functionality that de-registers mobile stations that do not originate or receives any
connections.When a modem not is registered its not possible to make any outgoing or
incoming connections. Some networks de-registers a fixed “idle” user after 2–3 weeks
and some other network operators does not have this functionality at all. However, this
problem can be solved with a AT-command <AT+WRST> which allows the user to
configure a timeout period after which the modem will make a reset and re-register to
the network. Please refer to the AT-command listing in this manual.The network opera-
tor should also be able to provide information whether this function is enabled or not.
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