Once you have determined the Endpoints within the Zones for the Lotus Sametime Unified Telephony system, you can create Aliases and, at the same time, associate these Aliases with the Endpoints. The Endpoint Alias function lists the Endpoint Aliases registered with an endpoint. For SIP endpoints, up to five aliases are allowed. All Aliases created within Lotus Sametime Unified Telephony must be unique. This is because these Aliases are used to determine where a received SIP request originated.
An alias can be an IP address, an FQDN or the combination of IP address/FQDN and a port separated by a colon:
Type of Alias
The type of each Alias for a SIP Endpoint must should be set to SIP URL. In addition, the Lotus Sametime Unified Telephony stores only the user information part (user name or telephone number) of the Endpoint's address-of-record ("userinfo@host") as the SIP Endpoint's Alias.
An alias is unique according to its combined name and type. The administrator can create more than one alias with the same name however the type must be different.
Aliases for Endpoints
To know which aliases need to be entered for endpoints, the administrator needs to know the contents of the SIP messages that the endpoints sends to Lotus Sametime Unified Telephony. Most requests contain a Contact header and Lotus Sametime Unified Telephony will add the host part of the Contact header to the Alias lookup. Some messages do not contain a host header. For these messages, Lotus Sametime Unified Telephony uses the host of the Bottom Via header for the Alias lookup. For endpoints that register, the user part (or the user@host part) of the From header of the REGISTER request is used for the Alias lookup.
Aliases for Subscribers
Requests from subscribers are recognized by looking up the user or user@host part of the received From header as Aliases.
Aliases for Hosting
In a hosted environment, multiple Business Groups can be spanned across Lotus Sametime Unified Telephony systems by setting up so-called 'virtual endpoints'.
A virtual endpoint is an endpoint that is created with a single Alias that is an FQDN that resolves to the own SIP server as IP address. As long as the endpoint uses that same FQDN to send SIP requests to Lotus Sametime Unified Telephony, it will be recognized by this FQDN (which is the host part of the Request URI) rather than by the host part of the Contact header or the bottom Via header.
The Lotus Sametime Unified Telephony SIP registrar supports dynamic and static (permanent) alias registrations, and performs alias translation to resolve aliases to an IP transport address, when it receives a call request from the endpoint. If another server manages the endpoint, the aliases are translated into the call signaling transport address of the far-end server.
As the request URI of a SIP request always points to the intended target Lotus Sametime Unified Telephonysystem, this results in the following:
Parent topic: Routing and Translation
- The Lotus Sametime Unified Telephony that is sending the request must be set up to use FQDNs rather than IP addresses in the Primary Signaling field because this FQDN will beused by the target Lotus Sametime Unified Telephony as an alias to find the Lotus Sametime Unified Telephony that sent therequest.
- The Lotus Sametime Unified Telephony that is receiving the request must configure the FQDN received inthe domain part of the Request URI as an alias for the endpoint that represents the sending Lotus Sametime Unified Telephony.