I've dumped a call between two lync clients and saw that there were some UDP packets that look like this:
Server -> Client
1132 14.495362000 <serverip> <clientip> STUN 146 Binding Request user: ????:????
Client -> Server:
1133 14.499136000 <clientip> <serverip> STUN 130 Binding Success Response XOR-MAPPED-ADDRESS: <serverip>:54019 user: ????:????
????:???? - ? is a character from the alphabet
If I read the RFC correctly this is not a security issue, is that correct?