An improved arrangement is described for maintaining throughput of data packets over a cellular packet network from an Internet server to an end user machine during handoff of a mobile subscriber unit from a first base station to a second base station. The end user machine conventionally generates, in response to successive bytes from the server, acknowledgment signals including where applicable a "zero" acknowledgment signal that advertises a closed receive window at the end user machine and that is effective to pause transmission of data from the server. In response to a handoff start signal from the subscriber unit, a gateway unit associated with the first base station sends to the server a simulated zero acknowledgment signal to pause such transmission. Upon completion of handoff, an actual non-zero acknowledgment signal stored at the gateway unit at the start of handoff is applied to the server to resume transmission from the server to the end user machine.