Disclaimer: This information was received and posted with permission by resources in the Sametime Level 2 support team. It is provided as is for reference only and subject to change. A common question when working with the Sametime Gateway is how requests route between the gateway, and the Sametime community. When setting up the gateway the only connection you define is from the gateway to one Sametime sever in the community. From there the gateway will discover the other servers in the community. Inbound and outbound requests are handled differently “Inbound requests (external user adds internal, external initiates a chat) are forwarded Round Robin by the Gateway server to the next server in the round robin list. This can be any server that is in the Sametime Community. The Sametime server that gets the inbound requests does the lookup on the user being subscribed too. If the community server that got the request isn’t the server that the internal user is connected to, then the request will be routed (internally, among the ST servers themselves) to the correct Sametime server. This would be for both request to add user to contact lists and the chats themselves. In a non-clustered environment where a Sametime Home Server is specified, the Gateway server will still round robin these inbound requests to the next server, but the Sametime server will now use the SametimeServer value to route the communication to the user’s home server. This would be different than routing it to the server he is logged into. Outbound is different. (Internal user adds external user) The server the user is physically connected to does the lookup on outbound ” The key here is that all servers in your local Sametime community regardless of the service they provide, must be accessible to the Sametime gateway on port 1516, in addition in the LDAP Server of your stconfig.nsf you need to make sure the search filters can resolve the e-mail address on all the servers as well. 