Since the PDU line doesn't have a prefix, the parser can get confused
if other unsolicited notifications arrive. There is already explicit
support for unsolicited notifications with PDU, so we use that
instead
- Can receive 7Bit, 8Bit and UCS2 encoded messages
- 8Bit is assumed to be a datagram to a certain port
- Messages with Invalid format are ignored
- Concatenation not yet supported