A router receives from a host service a message which is intended for delivery to a mobile device via a wireless network. The message includes an indication field which includes a return packet indication on whether to send a return packet to the host, an identifier field which includes an identifier which identifies the device, and a payload field which includes a payload of the message. When the indication is set to a first, setting and the message is not being delivered to the device, the router sends to the host a return packet which indicates that the message is not being delivered to the device. When the indication is set to a second setting and the message is not being delivered to the device, the router does not send to the host the return packet which indicates that the message is not being delivered to the device.