Methods and apparatus are disclosed for obtaining information from one or more headers of a data item transmitted via a communication network, a predetermined portion of at least one header carrying a symbol or combination of symbols having a first pre-defined meaning according to a first pre-defined communication protocol. The method comprises inspecting at least one header of a received data item whereby to identify the symbol or combination of symbols carried by the predetermined portion thereof; identifying whether at least one other portion of a header of the data item is carrying the same symbol or combination of symbols; and in the event that it is identified that at least one other portion of a header of the data item is carrying the same symbol or combination of symbols, ‘interpreting and/or processing at least one of the one or more headers according to a second pre-defined communication protocol, the second communication protocol differing from the first communication protocol.