Writes UDP data to the remote connection. Must be wrapped between beginPacket() and endPacket(). beginPacket() initializes the packet of data, it is not sent until endPacket() is called.
GSMUDP.write(byte); GSMUDP.write(buffer, size);
byte: the outgoing byte buffer: the outgoing message size: the size of the buffer
single byte into the packet bytes size from buffer into the packet