1. An Instant Messaging (IM) communication system, comprising: an IM server in a communication center, the IM server connected to a public data-packet-network and to a private data-packet-network, the private data-packet-network further connecting computerized workstations used by agents of the communication center; first data storage device storing a set of routing rules for the communication center; and stored a second data storage device storing agent data for the communication center, the data including agent availability and IM capability relative to one or more IM service protocols; wherein the IM server receives IM messages from two or more external IM servers using , wherein the two or more external IM servers use at least two different IM service protocols , via the public data-packet-network, the IM messages representing desired communication between specific clients of the external IM servers and agents of the communication center, consults the communication center routing rules, IM service protocol capabilities the IM capability of the agents, and the stored agent data to select available agents with the needed based on the IM service protocols that is detected to be needed , and establishes IM communication between the specific clients and the selected agents via the private data-packet-network , for exchanging the IM messages between the specific clients and the agents, and wherein the IM server in the communication center, in the event of receiving an IM notification from one of the specific clients, conducts IM communication with the one of the specific clients initiating the notification, elicits information from the one of the specific clients, identifies parameters relating to an IM application used by the one of the specific clients, and uses the elicited information along with the identified parameters relating to the IM application, the agent data, and availability, to determine a capable and available agent with whom to establish the IM communication for the one of the specific clients .