Anyone seen this HTTP header? I get it on a mobile web application when a browser on Orange UK’s network hits my site. It’s interesting if it’s some kind of unique ID. Googling for it returns absolutely no results, which is kind of scary! The value is a base64 encoded string of 16 bytes of binary, so it’s not giving much away. On the same requests I see other proprietary headers from the Nokia WAP Gateway software (version 4.0 in this case). I need to do more testing to see if a) it varies between different handsets/SIMs and b) it’s consistent for a given handset/SIM.

EDIT: Seems like the ID changes between hits from the same phone. Perhaps it’s more like a session identifier than a unique device/SIM/user ID.