With Sametime 9 an extranet license is not required to communicate with external users. Putting the Gateway aside and to some extent meetings how else can users communicate externally?
Looking at the ST9 announcement letter
I see a reference to "Anonymous access for external participants" under the "Instant messaging" section. Reading further I see the following:
"IBM Sametime Communicate V9.0 is available under a per Authorized User (AU) charge metric. Under the AU charge metric, Authorized Users may use their entitlement to communicate with External Users without requiring a separate entitlement for those External Users. For example, an Authorized User can distribute IBM Sametime Connect Clients to External Users for the sole purpose of accessing the Authorized User's Servers. An External User is a unique person,
not employed in, paid by, or acting on behalf of licensee's enterprise, who is given access to the program in any manner directly or indirectly (for example, via a multiplexing program, device, or application server) through any means by an Authorized User entitled to use the program to communicate only with those same entitled users."
In a meeting a guest can join and communicate with others in the confines of the meeting but is it possible for that same guest to communicate with LDAP users outside of a meeting?
In ST 8.5 there was an option to "log in as guest" but that was removed some time ago. I guess it doesn't make sense to have people logging in who cannot have a buddy list etc.
I read that there is a way to login anonymously using the STProxy SDK but that requires some development work.
I am assuming that by adding external users to your LDAP you can explain that they are external users when/if IBM check your licensing? This would allow these external users to use a Connect client or STProxy web client to log in. Unfortunately it could also allow them to access other SSO enabled applications.