Prior to joining a device to a network, the device is connected to an external system via a local connection. The external system provides the device with a local time stamp that includes a local time value and a local time error value. The device may use the time information to communicate with the external system. After the device is joined to the network, the device may transmit a communication on the network that includes time information. If so, then the communication includes a time value based on the device's time value and a time error value set to a value indicating a maximum error. The network is protected from potentially poor quality time information. Any device that receives the communication rejects the time information since the time error value indicates a maximum error.