This paper proposes an analytical voltage estimation method for the power packet dispatching network. A unit power packet consists of signals and DC pulsed voltage waveform. In the network, power packets are transmitted among power packet routers (routers) by time-division multiplexing. Routers have capacitors as the storage of power during the power transmission. The power flows depending on the voltage gradient among the storage. The power flow in the network has been studied with numerical approaches. However, the existing studies have considered transmission losses but ignored transient responses. Considering transient responses, the power transmission analysis generally requires circuit simulation and takes considerable time. This paper focuses on a one-to-one connection between routers and underdamped conditions. They allow the estimation of storage voltages considering the transient responses without circuit simulation. First, theoretical analysis and experimental verification are performed on the conditions. Then, an analytical voltage estimation method is proposed by expanding the analysis of the one-to-one connection to the network. Comparison with circuit simulation reveals that the estimation method is accurate enough to analyze power transmission in the network. Comment: This paper was submitted to Nonlinear Theory and Its Applications, IEICE on December 28, 2021