Before revision:  Using insights from service communication data, we model the service interactions using self-exciting and mutually exciting bivariate Hawkes processes, so that a correspondence from one party increases the likelihood of a response from the other party soon after. Moreover, our models incorporate both dynamic busyness factors that depend on the agent workload as well as dynamic factors that depend on the inner-mechanics of the interaction.
After revision:  A key observation is that the customer and agent's co-produced service has cross- and self-exciting dynamics within each conversation. The cross-excitation stems from the two parties responding to one another, and the self-excitation captures one party sending follow-ups to their own prior message. We capture this phenomenon by introducing Hawkes process models of the inner-mechanics of the interaction.