An arrangement and method for reducing memory usage for communications between servers in a communication network utilizing the Session Initiation Protocol (SIP) by controlling establishment of SIP dialogues. A single SIP dialogue for a certain event package is utilized for multiple subscriptions between one instance of a requesting server such as a Resource List Server (RLS) and one instance of an Application Server such as, for example, a Presence Server. The SIP dialogue is then used to send all SIP NOTIFY messages between these two entities to reduce memory usage at both ends by removing the overhead created by SIP.