Per our support engineer:
Regarding following issue, our buddy has 2 questions on SIP standard in LCS.
1) How to register from a SIP client which doesn't support NTLS or Kerberos
2) Does LCS support HTTP Digest Authentication
LCS can choose one of the following based on server settings:
- Kerberos and NTLM (default)
Communicator (Client) doesn't have UI controls for this - it will simply choose Kerberos if presented - if not, it will select NTLM. If presented with both, it will always choose Kerberos.
Moreover, I don’t think LCS has build-in feature of HTTP Digest Authentication. By default, we only support NTLM and Kerberos authentication.
-brend (ISV Buddy Team)