Greeting the caller, reporting that all the operators are busy at the moment, plays music during waiting in queue, requests to stay on the line as the next available operator will pick up exactly your call.
AddPac AP-GS1004A is one of the models of inter-network VoIP GSM gateways, through which, it is possible to format a single network unit and to use it for VoIP-telephony, analog communication lines and GSM-network.