The Representative AS is the application server which allocates the user to the application servers and keeps the user allocation information and relevant data for the service during the duration of a session or longer than that. The incoming call for the service is received and forwarded to the allocated application server by the Representative AS.
The following points are considered as requirements for the dynamic user allocation procedures using the representative AS.
The representative AS for each service is the initial contact point for all signalling. This can include ISC; and for example, Ut; and others signalling that may or may not be defined in 3GPP.
For the ISC, the representative AS is included in every message which opens a new dialogue. It is not included after the initial transaction.
For example, when the AS is to be invoked by evaluating the iFC at the S-CSCF, the address in the iFC is the address of the Representative AS.
The following figure shows an example service deployment for three different services using the representative AS.