Hello List, Can anyone recommend some SIP Instant Messaging UA (linux and windows) that follows the specification word by word? I tried MSN Messenger 4.6 and 5 - both appears to have some problems (version 5 tries to send a MESSAGE with the INVITE method and gets back a BYE in response!!!!!!!!!!!!!). Thanks in advance, Dhiraj Bhuyan Security Research Engineer BT Exact Tel: +44 1473 643932 Mob: +44 7962 012145 Email: dhiraj.2.bhuyan(a)bt.com