// Zero for location messages
buf.readByte(); // voltage
buf.readByte(); // gsm signal
String imei = readImei(buf);
long index = buf.readUnsignedShort();
int type = buf.readUnsignedByte();
if (type == MSG_HEARTBEAT) {
if (channel != null) {
byte[] response = {0x54, 0x68, 0x1A, 0x0D, 0x0A};