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-Tunnels. A single SIP-Tunnel 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-Tunnel 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.