M E R L I N U 7 4 0 U S E R G U I D E 2 9
GU-90023
Revision A
NOTE: WHEN THE MODEM TRANSITIONS FROM ONE STATE TO ANOTHER, THE ACTUAL LED DISPLAY WILL NOT
CHANGE IMMEDIATELY, RATHER, IT WILL ONLY CHANGE ONCE THE MODEM HAS CONFIRMED THAT THE NEW STATE
IS VALID. FOR EXAMPLE, WHEN THE MODEM IS TAKEN OUT OF A SERVICE AREA IT MIGHT TAKE THE MODEM 10 TO
90 SECONDS TO CONFIRM THAT NO SERVICE IS AVAILABLE AT WHICH TIME THE LED DISPLAY WILL CHANGE STATES
ACCORDINGLY
PDP (Packet Data Protocol) Context Activation Process: To connect to a PDN (Packet Data Network), such as the
Internet, some sort of session description information needs to exist (i.e. type of IP network, quality of service, IP
address etc…) to enable agreement on the characteristics of any data flow between the network and the mobile terminal.
This is essentially, what PDP ‘context’ activation is.
Circuit Switched (CS) Data connection is basically similar to a land line modem dial up call. A dedicated connection is set
up for the duration of the call regardless of whether data is transferred or not.
A Packet Switched (PS) Data connection is typically set up once. Within packet-switched networks, data is divided
(disassembled and packaged) into packets before it is sent. Packets are routed through the networks based on a
destination address contained within each packet. Once all the packets arrive at their respective destinations, the data is
recompiled (unpacked and assembled). There is no need to re-establish the connection before each transmission.
