A web-based hosted solution (a managed service or system) through which business entities create and manage communications campaigns, such as interactive campaigns that afford target recipients an opportunity to be connected to a call center. To reduce latency of customer-to-agent connections, the system implements an agent stay-on-line function by which a persistent telephony connection is established and maintained between the system infrastructure and an available agent. In this manner, the agent may handle multiple customers while avoiding an ACD hold queue. In addition, preferably a service-side hold queue also is established and maintained on the service-side of the infrastructure. This hold queue maintains calls that are waiting to be connected to available agents. It ensures that any customer abandons (on the service side) do not impair the connections that are being established and maintained to the agents. The managed service carries out a communications campaign on behalf of a client. A “campaign” refers to a series of calls to a contact list using one or more sub-campaigns. A sub-campaign associates a list of contacts, a script, and a timeframe.