After a couple of minutes, my SMPP connection is suddenly disconnected. What happens?
SMPP uses a link keep alive timer (enquire interval). Once in every x seconds the client should send an enquire_link packet to the SMPP server, if this packet is not received the SMPP server will close the connection. This will also happen if your enquire_link timer is set to high. Please try to set the keep alive timer to a lower value. This can be done from the SMPP channel properties window in the channel view of the SMS Server Manager application.