Device coverage depends on where you are, the device you are using and whether it has an external antenna attached.
You should be aware that the Telstra coverage maps displayed have been created using tools that predict the likely areas of outdoor coverage. We have not individually tested every particular location within the identified coverage areas for coverage, nor any indoor locations or sub-surface areas. This means that while the footprint of coverage outlined on the maps is generally accurate, there will be specific areas described as being within a coverage area where your device will not work. This is a common characteristic of wireless systems. For example, actual coverage could be degraded or not existent in specific locations due to certain physical structures or geographic features or as a result of the device used. Physical structures which may block or inhibit coverage could include basements, lifts, underground car parks, concrete buildings, tunnels and road cuttings. The specific nature of building materials used in an office or dwelling also impacts on the coverage within, with some materials such as steel framing and metallic window films having a significant impact on coverage within a building. Geographic features which may block or inhibit coverage could include formations such as hills and mountains or even trees.
The offshore coverage shown is only indicative of where a device may operate. Factors beyond Telstra's control such as the weather, tides, sea conditions and your antenna installation (type and height of antenna above sea level) can significantly influence the actual user experience of coverage, data speed and performance. Public mobile networks must not be relied upon as a primary method of emergency communication at sea.
Data speeds experienced on Telstra's mobile networks may be affected by network availability, the type and configuration of customer equipment, or device used, the performance of external networks (for example the Internet), the signal strength available to the device, and other factors such as the type of application.