Cubeblue Ltd. has developed a GSM modem for the electricity metering industry, which plugs directly into the 25-way or 9-way connections on the electronic polyphase meter fitting under the cover, taking its power from the meter. This means that a separate power supply is not necessary, as long as the meter provides more than 60mA. It is powered by an integrated lithium ion battery with full protection, that allows the unit to operate independently of the meter, and can be used to check meter status if a network problem exists, or as a test unit to check signal strength prior to installation.
The system uses standard Hayes AT commands to control set-up, with special additional commands provided by Cubeblue. The units are fitted with a locking SIM carrier which is internally mounted. Access to the SIM can thus only be gained by the installer, and it can only be removed by stripping down the unit. There is no obvious indication that the unit is a GSM device, as the SIM carrier is not visible. Although the SIMs are locked to a data tariff, it is still possible to send SMS messages if the SIM is inserted into a mobile phone.
The high cost of the unit over the existing PSTN option is overcome by the ability to connect the unit almost anywhere, without any additional costs for line installation. It can also be installed with the meter. Cubeblue is able to offer a number of GSM data tariff options that include an £2.50 monthly line rental agreement.