Each WindTalker weather station communicates over a mobile phone network and therefore requires an active SIM card. When selecting a suitable SIM card, you need to consider the following factors:

• Signal Strength - The most important thing is network coverage, if you don't have a good reliable signal your weather station will not be able to transmit weather reports. It's important to check that you have network coverage that includes GPRS data (we don’t need 3G connectivity).
• Data Cost - WindTalkers only send small amounts of data at regular intervals - the default frequency between weather reports is every 5 minutes.  A package which allows approximately 250MB per month is sufficient using the default report frequency. Periodically, we check the market for the best deals, so give us a call and we'll help you find the best package in your area. As part of a site survey we advise on the best network provider for your weather station.

For more details on SIM cards, see http://en.wikipedia.org/wiki/Subscriber_Identity_Module.